diff --git a/adminer/call.inc.php b/adminer/call.inc.php
index 4bc37972..be3a7571 100644
--- a/adminer/call.inc.php
+++ b/adminer/call.inc.php
@@ -94,7 +94,7 @@ if ($in) {
 /** Format string as table row
 * @return string HTML
 */
-function pre_tr(string $s) {
+function pre_tr(string $s): string {
 	return preg_replace('~^~m', '<tr>', preg_replace('~\|~', '<td>', preg_replace('~\|$~m', "", rtrim($s))));
 }
 
diff --git a/adminer/drivers/mysql.inc.php b/adminer/drivers/mysql.inc.php
index 2f67494f..7071eb9d 100644
--- a/adminer/drivers/mysql.inc.php
+++ b/adminer/drivers/mysql.inc.php
@@ -84,9 +84,8 @@ if (!defined('Adminer\DRIVER')) {
 			}
 
 			/** Set the client character set
-			* @return bool
 			*/
-			function set_charset(string $charset) {
+			function set_charset(string $charset): bool {
 				if (function_exists('mysql_set_charset')) {
 					if (mysql_set_charset($charset, $this->link)) {
 						return true;
@@ -137,21 +136,21 @@ if (!defined('Adminer\DRIVER')) {
 			/** Fetch next row as associative array
 			* @return array<?string>
 			*/
-			function fetch_assoc() {
+			function fetch_assoc(): array {
 				return mysql_fetch_assoc($this->result);
 			}
 
 			/** Fetch next row as numbered array
 			* @return list<?string>
 			*/
-			function fetch_row() {
+			function fetch_row(): array {
 				return mysql_fetch_row($this->result);
 			}
 
 			/** Fetch next field
 			* @return object properties: name, type (0 number, 15 varchar, 254 char), charsetnr (63 binary); optionally: table, orgtable, orgname
 			*/
-			function fetch_field() {
+			function fetch_field(): object {
 				$return = mysql_fetch_field($this->result, $this->offset++); // offset required under certain conditions
 				$return->orgtable = $return->table;
 				$return->charsetnr = ($return->blob ? 63 : 0);
@@ -357,16 +356,14 @@ if (!defined('Adminer\DRIVER')) {
 
 
 	/** Escape database identifier
-	* @return string
 	*/
-	function idf_escape(string $idf) {
+	function idf_escape(string $idf): string {
 		return "`" . str_replace("`", "``", $idf) . "`";
 	}
 
 	/** Get escaped table name
-	* @return string
 	*/
-	function table(string $idf) {
+	function table(string $idf): string {
 		return idf_escape($idf);
 	}
 
@@ -394,7 +391,7 @@ if (!defined('Adminer\DRIVER')) {
 	/** Get cached list of databases
 	* @return list<string>
 	*/
-	function get_databases(bool $flush) {
+	function get_databases(bool $flush): array {
 		// SHOW DATABASES can take a very long time so it is cached
 		$return = get_session("dbs");
 		if ($return === null) {
@@ -410,25 +407,22 @@ if (!defined('Adminer\DRIVER')) {
 	/** Formulate SQL query with limit
 	* @param string $query everything after SELECT
 	* @param string $where including WHERE
-	* @return string
 	*/
-	function limit(string $query, string $where, int $limit, int $offset = 0, string $separator = " ") {
+	function limit(string $query, string $where, int $limit, int $offset = 0, string $separator = " "): string {
 		return " $query$where" . ($limit !== null ? $separator . "LIMIT $limit" . ($offset ? " OFFSET $offset" : "") : "");
 	}
 
 	/** Formulate SQL modification query with limit 1
 	* @param string $query everything after UPDATE or DELETE
-	* @return string
 	*/
-	function limit1(string $table, string $query, string $where, string $separator = "\n") {
+	function limit1(string $table, string $query, string $where, string $separator = "\n"): string {
 		return limit($query, $where, 1, 0, $separator);
 	}
 
 	/** Get database collation
 	* @param string[][] $collations result of collations()
-	* @return string
 	*/
-	function db_collation(string $db, array $collations) {
+	function db_collation(string $db, array $collations): string {
 		$return = null;
 		$create = get_val("SHOW CREATE DATABASE " . idf_escape($db), 1);
 		if (preg_match('~ COLLATE ([^ ]+)~', $create, $match)) {
@@ -441,16 +435,15 @@ if (!defined('Adminer\DRIVER')) {
 	}
 
 	/** Get logged user
-	* @return string
 	*/
-	function logged_user() {
+	function logged_user(): string {
 		return get_val("SELECT USER()");
 	}
 
 	/** Get tables list
 	* @return string[] [$name => $type]
 	*/
-	function tables_list() {
+	function tables_list(): array {
 		return get_key_vals("SELECT TABLE_NAME, TABLE_TYPE FROM information_schema.TABLES WHERE TABLE_SCHEMA = DATABASE() ORDER BY TABLE_NAME");
 	}
 
@@ -458,7 +451,7 @@ if (!defined('Adminer\DRIVER')) {
 	* @param list<string> $databases
 	* @return int[] [$db => $tables]
 	*/
-	function count_tables(array $databases) {
+	function count_tables(array $databases): array {
 		$return = array();
 		foreach ($databases as $db) {
 			$return[$db] = count(get_vals("SHOW TABLES IN " . idf_escape($db)));
@@ -470,7 +463,7 @@ if (!defined('Adminer\DRIVER')) {
 	* @param bool $fast return only "Name", "Engine" and "Comment" fields
 	* @return TableStatus[]
 	*/
-	function table_status(string $name = "", bool $fast = false) {
+	function table_status(string $name = "", bool $fast = false): array {
 		$return = array();
 		foreach (
 			get_rows(
@@ -497,24 +490,22 @@ if (!defined('Adminer\DRIVER')) {
 
 	/** Find out whether the identifier is view
 	* @param TableStatus $table_status
-	* @return bool
 	*/
-	function is_view(array $table_status) {
+	function is_view(array $table_status): bool {
 		return $table_status["Engine"] === null;
 	}
 
 	/** Check if table supports foreign keys
 	* @param TableStatus $table_status result of table_status1()
-	* @return bool
 	*/
-	function fk_support(array $table_status) {
+	function fk_support(array $table_status): bool {
 		return preg_match('~InnoDB|IBMDB2I' . (min_version(5.6) ? '|NDB' : '') . '~i', $table_status["Engine"]);
 	}
 
 	/** Get information about fields
 	* @return Field[]
 	*/
-	function fields(string $table) {
+	function fields(string $table): array {
 		global $connection;
 		$maria = ($connection->flavor == 'maria');
 		$return = array();
@@ -568,7 +559,7 @@ if (!defined('Adminer\DRIVER')) {
 	/** Get table indexes
 	* @return Index[]
 	*/
-	function indexes(string $table, ?Db $connection2 = null) {
+	function indexes(string $table, ?Db $connection2 = null): array {
 		$return = array();
 		foreach (get_rows("SHOW INDEX FROM " . table($table), $connection2) as $row) {
 			$name = $row["Key_name"];
@@ -583,7 +574,7 @@ if (!defined('Adminer\DRIVER')) {
 	/** Get foreign keys in table
 	* @return ForeignKey[]
 	*/
-	function foreign_keys(string $table) {
+	function foreign_keys(string $table): array {
 		global $driver;
 		static $pattern = '(?:`(?:[^`]|``)+`|"(?:[^"]|"")+")';
 		$return = array();
@@ -614,14 +605,14 @@ if (!defined('Adminer\DRIVER')) {
 	/** Get view SELECT
 	* @return array{select:string}
 	*/
-	function view(string $name) {
+	function view(string $name): array {
 		return array("select" => preg_replace('~^(?:[^`]|`[^`]*`)*\s+AS\s+~isU', '', get_val("SHOW CREATE VIEW " . table($name), 1)));
 	}
 
 	/** Get sorted grouped list of collations
 	* @return string[][]
 	*/
-	function collations() {
+	function collations(): array {
 		$return = array();
 		foreach (get_rows("SHOW COLLATION") as $row) {
 			if ($row["Default"]) {
@@ -638,17 +629,15 @@ if (!defined('Adminer\DRIVER')) {
 	}
 
 	/** Find out if database is information_schema
-	* @return bool
 	*/
-	function information_schema(string $db) {
+	function information_schema(string $db): bool {
 		return ($db == "information_schema")
 			|| (min_version(5.5) && $db == "performance_schema");
 	}
 
 	/** Get escaped error message
-	* @return string
 	*/
-	function error() {
+	function error(): string {
 		global $connection;
 		return h(preg_replace('~^You have an error.*syntax to use~U', "Syntax error", $connection->error));
 	}
@@ -662,9 +651,8 @@ if (!defined('Adminer\DRIVER')) {
 
 	/** Drop databases
 	* @param list<string> $databases
-	* @return bool
 	*/
-	function drop_databases(array $databases) {
+	function drop_databases(array $databases): bool {
 		$return = apply_queries("DROP DATABASE", $databases, 'Adminer\idf_escape');
 		restart_session();
 		set_session("dbs", null);
@@ -673,9 +661,8 @@ if (!defined('Adminer\DRIVER')) {
 
 	/** Rename database from DB
 	* @param string $name new name
-	* @return bool
 	*/
-	function rename_database(string $name, string $collation) {
+	function rename_database(string $name, string $collation): bool {
 		$return = false;
 		if (create_database($name, $collation)) {
 			$tables = array();
@@ -694,9 +681,8 @@ if (!defined('Adminer\DRIVER')) {
 	}
 
 	/** Generate modifier for auto increment column
-	* @return string
 	*/
-	function auto_increment() {
+	function auto_increment(): string {
 		$auto_increment_index = " PRIMARY KEY";
 		// don't overwrite primary key by auto_increment
 		if ($_GET["create"] != "" && $_POST["auto_increment_col"]) {
@@ -773,9 +759,8 @@ if (!defined('Adminer\DRIVER')) {
 
 	/** Run commands to truncate tables
 	* @param list<string> $tables
-	* @return bool
 	*/
-	function truncate_tables(array $tables) {
+	function truncate_tables(array $tables): bool {
 		return apply_queries("TRUNCATE TABLE", $tables);
 	}
 
@@ -798,9 +783,8 @@ if (!defined('Adminer\DRIVER')) {
 	/** Move tables to other schema
 	* @param list<string> $tables
 	* @param list<string> $views
-	* @return bool
 	*/
-	function move_tables(array $tables, array $views, string $target) {
+	function move_tables(array $tables, array $views, string $target): bool {
 		global $connection;
 		$rename = array();
 		foreach ($tables as $table) {
@@ -827,9 +811,8 @@ if (!defined('Adminer\DRIVER')) {
 	/** Copy tables to other schema
 	* @param list<string> $tables
 	* @param list<string> $views
-	* @return bool
 	*/
-	function copy_tables(array $tables, array $views, string $target) {
+	function copy_tables(array $tables, array $views, string $target): bool {
 		queries("SET sql_mode = 'NO_AUTO_VALUE_ON_ZERO'");
 		foreach ($tables as $table) {
 			$name = ($target == DB ? table("copy_$table") : idf_escape($target) . "." . table($table));
@@ -864,7 +847,7 @@ if (!defined('Adminer\DRIVER')) {
 	* @param string $name trigger name
 	* @return Trigger
 	*/
-	function trigger(string $name, string $table) {
+	function trigger(string $name, string $table): array {
 		if ($name == "") {
 			return array();
 		}
@@ -875,7 +858,7 @@ if (!defined('Adminer\DRIVER')) {
 	/** Get defined triggers
 	* @return array{string, string}[]
 	*/
-	function triggers(string $table) {
+	function triggers(string $table): array {
 		$return = array();
 		foreach (get_rows("SHOW TRIGGERS LIKE " . q(addcslashes($table, "%_\\"))) as $row) {
 			$return[$row["Trigger"]] = array($row["Timing"], $row["Event"]);
@@ -886,7 +869,7 @@ if (!defined('Adminer\DRIVER')) {
 	/** Get trigger options
 	* @return array{Timing: list<string>, Event: list<string>, Type: list<string>}
 	*/
-	function trigger_options() {
+	function trigger_options(): array {
 		return array(
 			"Timing" => array("BEFORE", "AFTER"),
 			"Event" => array("INSERT", "UPDATE", "DELETE"),
@@ -898,7 +881,7 @@ if (!defined('Adminer\DRIVER')) {
 	* @param 'FUNCTION'|'PROCEDURE' $type
 	* @return Routine
 	*/
-	function routine(string $name, $type) {
+	function routine(string $name, $type): array {
 		global $driver;
 		$aliases = array("bool", "boolean", "integer", "double precision", "real", "dec", "numeric", "fixed", "national char", "national varchar");
 		$space = "(?:\\s|/\\*[\s\S]*?\\*/|(?:#|-- )[^\n]*\n?|--\r?\n)";
@@ -935,30 +918,28 @@ if (!defined('Adminer\DRIVER')) {
 	/** Get list of routines
 	* @return list<string[]> ["SPECIFIC_NAME" => , "ROUTINE_NAME" => , "ROUTINE_TYPE" => , "DTD_IDENTIFIER" => ]
 	*/
-	function routines() {
+	function routines(): array {
 		return get_rows("SELECT ROUTINE_NAME AS SPECIFIC_NAME, ROUTINE_NAME, ROUTINE_TYPE, DTD_IDENTIFIER FROM information_schema.ROUTINES WHERE ROUTINE_SCHEMA = DATABASE()");
 	}
 
 	/** Get list of available routine languages
 	* @return list<string>
 	*/
-	function routine_languages() {
+	function routine_languages(): array {
 		return array(); // "SQL" not required
 	}
 
 	/** Get routine signature
 	* @param Routine $row result of routine()
-	* @return string
 	*/
-	function routine_id(string $name, array $row) {
+	function routine_id(string $name, array $row): string {
 		return idf_escape($name);
 	}
 
 	/** Get last auto increment ID
 	* @param Result $result or true
-	* @return string
 	*/
-	function last_id($result) {
+	function last_id($result): string {
 		return get_val("SELECT LAST_INSERT_ID()"); // mysql_insert_id() truncates bigint
 	}
 
@@ -979,9 +960,8 @@ if (!defined('Adminer\DRIVER')) {
 	}
 
 	/** Get SQL command to create table
-	* @return string
 	*/
-	function create_sql(string $table, bool $auto_increment, string $style) {
+	function create_sql(string $table, bool $auto_increment, string $style): string {
 		$return = get_val("SHOW CREATE TABLE " . table($table), 1);
 		if (!$auto_increment) {
 			$return = preg_replace('~ AUTO_INCREMENT=\d+~', '', $return); //! skip comments
@@ -990,23 +970,20 @@ if (!defined('Adminer\DRIVER')) {
 	}
 
 	/** Get SQL command to truncate table
-	* @return string
 	*/
-	function truncate_sql(string $table) {
+	function truncate_sql(string $table): string {
 		return "TRUNCATE " . table($table);
 	}
 
 	/** Get SQL command to change database
-	* @return string
 	*/
-	function use_sql(string $database) {
+	function use_sql(string $database): string {
 		return "USE " . idf_escape($database);
 	}
 
 	/** Get SQL commands to create triggers
-	* @return string
 	*/
-	function trigger_sql(string $table) {
+	function trigger_sql(string $table): string {
 		$return = "";
 		foreach (get_rows("SHOW TRIGGERS LIKE " . q(addcslashes($table, "%_\\")), null, "-- ") as $row) {
 			$return .= "\nCREATE TRIGGER " . idf_escape($row["Trigger"]) . " $row[Timing] $row[Event] ON " . table($row["Table"]) . " FOR EACH ROW\n$row[Statement];;\n";
@@ -1017,21 +994,21 @@ if (!defined('Adminer\DRIVER')) {
 	/** Get server variables
 	* @return list<string[]> [[$name, $value]]
 	*/
-	function show_variables() {
+	function show_variables(): array {
 		return get_rows("SHOW VARIABLES");
 	}
 
 	/** Get status variables
 	* @return list<string[]> [[$name, $value]]
 	*/
-	function show_status() {
+	function show_status(): array {
 		return get_rows("SHOW STATUS");
 	}
 
 	/** Get process list
 	* @return list<string[]> [$row]
 	*/
-	function process_list() {
+	function process_list(): array {
 		return get_rows("SHOW FULL PROCESSLIST");
 	}
 
@@ -1054,9 +1031,8 @@ if (!defined('Adminer\DRIVER')) {
 	/** Convert value in edit after applying functions back
 	* @param Field $field one element from fields()
 	* @param string $return SQL expression
-	* @return string
 	*/
-	function unconvert_field(array $field, string $return) {
+	function unconvert_field(array $field, string $return): string {
 		if (preg_match("~binary~", $field["type"])) {
 			$return = "UNHEX($return)";
 		}
@@ -1072,9 +1048,8 @@ if (!defined('Adminer\DRIVER')) {
 
 	/** Check whether a feature is supported
 	* @param literal-string $feature "check|comment|copy|database|descidx|drop_col|dump|event|indexes|kill|materializedview|partitioning|privileges|procedure|processlist|routine|scheme|sequence|status|table|trigger|type|variables|view|view_trigger"
-	* @return bool
 	*/
-	function support(string $feature) {
+	function support(string $feature): bool {
 		return !preg_match("~scheme|sequence|type|view_trigger|materializedview" . (min_version(8) ? "" : "|descidx" . (min_version(5.1) ? "" : "|event|partitioning")) . (min_version('8.0.16', '10.2.1') ? "" : "|check") . "~", $feature);
 	}
 
@@ -1087,16 +1062,15 @@ if (!defined('Adminer\DRIVER')) {
 	}
 
 	/** Return query to get connection ID
-	* @return string
 	*/
-	function connection_id() {
+	function connection_id(): string {
 		return "SELECT CONNECTION_ID()";
 	}
 
 	/** Get maximum number of connections
 	* @return numeric-string
 	*/
-	function max_connections() {
+	function max_connections(): string {
 		return get_val("SELECT @@max_connections");
 	}
 
@@ -1105,35 +1079,32 @@ if (!defined('Adminer\DRIVER')) {
 	/** Get user defined types
 	* @return string[] [$id => $name]
 	*/
-	function types() {
+	function types(): array {
 		return array();
 	}
 
 	/** Get values of user defined type
-	* @return string
 	*/
-	function type_values(int $id) {
+	function type_values(int $id): string {
 		return "";
 	}
 
 	/** Get existing schemas
 	* @return list<string>
 	*/
-	function schemas() {
+	function schemas(): array {
 		return array();
 	}
 
 	/** Get current schema
-	* @return string
 	*/
-	function get_schema() {
+	function get_schema(): string {
 		return "";
 	}
 
 	/** Set current schema
-	* @return bool
 	*/
-	function set_schema(string $schema, Db $connection2 = null) {
+	function set_schema(string $schema, Db $connection2 = null): bool {
 		return true;
 	}
 }
diff --git a/adminer/drivers/sqlite.inc.php b/adminer/drivers/sqlite.inc.php
index da72e888..f03cba46 100644
--- a/adminer/drivers/sqlite.inc.php
+++ b/adminer/drivers/sqlite.inc.php
@@ -461,9 +461,8 @@ if (isset($_GET["sqlite"])) {
 	* @param list<array{string, string, list<string>|'DROP'}> $indexes [[$type, $name, $columns]], empty to preserve
 	* @param string $drop_check CHECK constraint to drop
 	* @param string $add_check CHECK constraint to add
-	* @return bool
 	*/
-	function recreate_table(string $table, string $name, array $fields, array $originals, array $foreign, int $auto_increment = 0, $indexes = array(), string $drop_check = "", string $add_check = "") {
+	function recreate_table(string $table, string $name, array $fields, array $originals, array $foreign, int $auto_increment = 0, $indexes = array(), string $drop_check = "", string $add_check = ""): bool {
 		global $driver;
 		if ($table != "") {
 			if (!$fields) {
diff --git a/adminer/include/adminer.inc.php b/adminer/include/adminer.inc.php
index d42d1cd5..046103ac 100644
--- a/adminer/include/adminer.inc.php
+++ b/adminer/include/adminer.inc.php
@@ -10,14 +10,14 @@ class Adminer {
 	/** Name in title and navigation
 	* @return string HTML code
 	*/
-	function name() {
+	function name(): string {
 		return "<a href='https://www.adminer.org/'" . target_blank() . " id='h1'>Adminer</a>";
 	}
 
 	/** Connection parameters
 	* @return array{string, string, string}
 	*/
-	function credentials() {
+	function credentials(): array {
 		return array(SERVER, $_GET["username"], get_password());
 	}
 
@@ -30,28 +30,26 @@ class Adminer {
 	/** Get key used for permanent login
 	* @return string cryptic string which gets combined with password or false in case of an error
 	*/
-	function permanentLogin(bool $create = false) {
+	function permanentLogin(bool $create = false): string {
 		return password_file($create);
 	}
 
 	/** Return key used to group brute force attacks; behind a reverse proxy, you want to return the last part of X-Forwarded-For
-	* @return string
 	*/
-	function bruteForceKey() {
+	function bruteForceKey(): string {
 		return $_SERVER["REMOTE_ADDR"];
 	}
 
 	/** Get server name displayed in breadcrumbs
 	* @return string HTML code or null
 	*/
-	function serverName(string $server) {
+	function serverName(string $server): string {
 		return h($server);
 	}
 
 	/** Identifier of selected database
-	* @return string
 	*/
-	function database() {
+	function database(): string {
 		// should be used everywhere instead of DB
 		return DB;
 	}
@@ -59,34 +57,33 @@ class Adminer {
 	/** Get cached list of databases
 	* @return list<string>
 	*/
-	function databases(bool $flush = true) {
+	function databases(bool $flush = true): array {
 		return get_databases($flush);
 	}
 
 	/** Get list of schemas
 	* @return list<string>
 	*/
-	function schemas() {
+	function schemas(): array {
 		return schemas();
 	}
 
 	/** Specify limit for waiting on some slow queries like DB list
 	* @return float number of seconds
 	*/
-	function queryTimeout() {
+	function queryTimeout(): float {
 		return 2;
 	}
 
 	/** Headers to send before HTML output
-	* @return void
 	*/
-	function headers() {
+	function headers(): void {
 	}
 
 	/** Get Content Security Policy headers
 	* @return list<string[]> of arrays with directive name in key, allowed sources in value
 	*/
-	function csp() {
+	function csp(): array {
 		return csp();
 	}
 
@@ -94,7 +91,7 @@ class Adminer {
 	* @param bool $dark dark CSS: false to disable, true to force, null to base on user preferences
 	* @return bool true to link favicon.ico
 	*/
-	function head(bool $dark = null) {
+	function head(bool $dark = null): bool {
 		// this is matched by compile.php
 		echo "<link rel='stylesheet' href='../externals/jush/jush.css'>\n";
 		echo ($dark !== false ? "<link rel='stylesheet'" . ($dark ? "" : " media='(prefers-color-scheme: dark)'") . " href='../externals/jush/jush-dark.css'>\n" : "");
@@ -104,7 +101,7 @@ class Adminer {
 	/** Get URLs of the CSS files
 	* @return list<string>
 	*/
-	function css() {
+	function css(): array {
 		$return = array();
 		foreach (array("", "-dark") as $mode) {
 			$filename = "adminer$mode.css";
@@ -116,9 +113,8 @@ class Adminer {
 	}
 
 	/** Print login form
-	* @return void
 	*/
-	function loginForm() {
+	function loginForm(): void {
 		global $drivers;
 		echo "<table class='layout'>\n";
 		// this is matched by compile.php
@@ -136,9 +132,8 @@ class Adminer {
 	/** Get login form field
 	* @param string $heading HTML
 	* @param string $value HTML
-	* @return string
 	*/
-	function loginFormField(string $name, string $heading, string $value) {
+	function loginFormField(string $name, string $heading, string $value): string {
 		return $heading . $value . "\n";
 	}
 
@@ -156,7 +151,7 @@ class Adminer {
 	* @param TableStatus $tableStatus result of table_status1()
 	* @return string HTML code, "" to ignore table
 	*/
-	function tableName(array $tableStatus) {
+	function tableName(array $tableStatus): string {
 		return h($tableStatus["Name"]);
 	}
 
@@ -165,7 +160,7 @@ class Adminer {
 	* @param int $order order of column in select
 	* @return string HTML code, "" to ignore field
 	*/
-	function fieldName(array $field, int $order = 0) {
+	function fieldName(array $field, int $order = 0): string {
 		$type = $field["full_type"];
 		$comment = $field["comment"];
 		return '<span title="' . h($type . ($comment != "" ? ($type ? ": " : "") . $comment : '')) . '">' . h($field["field"]) . '</span>';
@@ -174,9 +169,8 @@ class Adminer {
 	/** Print links after select heading
 	* @param TableStatus $tableStatus result of table_status1()
 	* @param string $set new item options, NULL for no new item
-	* @return void
 	*/
-	function selectLinks(array $tableStatus, string $set = "") {
+	function selectLinks(array $tableStatus, string $set = ""): void {
 		global $driver;
 		echo '<p class="links">';
 		$links = array("select" => lang('Select data'));
@@ -206,31 +200,29 @@ class Adminer {
 	/** Get foreign keys for table
 	* @return ForeignKey[] same format as foreign_keys()
 	*/
-	function foreignKeys(string $table) {
+	function foreignKeys(string $table): array {
 		return foreign_keys($table);
 	}
 
 	/** Find backward keys for table
 	* @return BackwardKey[]
 	*/
-	function backwardKeys(string $table, string $tableName) {
+	function backwardKeys(string $table, string $tableName): array {
 		return array();
 	}
 
 	/** Print backward keys for row
 	* @param BackwardKey[] $backwardKeys result of $this->backwardKeys()
 	* @param string[] $row
-	* @return void
 	*/
-	function backwardKeysPrint(array $backwardKeys, array $row) {
+	function backwardKeysPrint(array $backwardKeys, array $row): void {
 	}
 
 	/** Query printed in select before execution
 	* @param string $query query to be executed
 	* @param float $start start time of the query
-	* @return string
 	*/
-	function selectQuery(string $query, float $start, bool $failed = false) {
+	function selectQuery(string $query, float $start, bool $failed = false): string {
 		global $driver;
 		$return = "</p>\n"; // required for IE9 inline edit
 		if (!$failed && ($warnings = $driver->warnings())) {
@@ -249,20 +241,19 @@ class Adminer {
 	* @param string $query query to be executed
 	* @return string escaped query to be printed
 	*/
-	function sqlCommandQuery(string $query) {
+	function sqlCommandQuery(string $query): string {
 		return shorten_utf8(trim($query), 1000);
 	}
 
 	/** Print HTML code just before the Execute button in SQL command
-	* @return void
 	*/
-	function sqlPrintAfter() {
+	function sqlPrintAfter(): void {
 	}
 
 	/** Description of a row in a table
 	* @return string SQL expression, empty string for no description
 	*/
-	function rowDescription(string $table) {
+	function rowDescription(string $table): string {
 		return "";
 	}
 
@@ -271,7 +262,7 @@ class Adminer {
 	* @param ForeignKey[] $foreignKeys
 	* @return list<string[]>
 	*/
-	function rowDescriptions(array $rows, array $foreignKeys) {
+	function rowDescriptions(array $rows, array $foreignKeys): array {
 		return $rows;
 	}
 
@@ -288,9 +279,8 @@ class Adminer {
 	* @param string $link link to foreign key
 	* @param Field $field single field returned from fields()
 	* @param string $original original value before applying editVal() and escaping
-	* @return string
 	*/
-	function selectVal(string $val, string $link, array $field, string $original) {
+	function selectVal(string $val, string $link, array $field, string $original): string {
 		$return = ($val === null ? "<i>NULL</i>"
 			: (preg_match("~char|binary|boolean~", $field["type"]) && !preg_match("~var~", $field["type"]) ? "<code>$val</code>"
 			: (preg_match('~json~', $field["type"]) ? "<code class='jush-js'>$val</code>"
@@ -304,18 +294,16 @@ class Adminer {
 
 	/** Value conversion used in select and edit
 	* @param Field $field single field returned from fields()
-	* @return string
 	*/
-	function editVal(string $val, array $field) {
+	function editVal(string $val, array $field): string {
 		return $val;
 	}
 
 	/** Print table structure in tabular format
 	* @param Field[] $fields data about individual fields
 	* @param TableStatus $tableStatus
-	* @return void
 	*/
-	function tableStructurePrint(array $fields, array $tableStatus = null) {
+	function tableStructurePrint(array $fields, array $tableStatus = null): void {
 		global $driver;
 		echo "<div class='scrollable'>\n";
 		echo "<table class='nowrap odds'>\n";
@@ -344,9 +332,8 @@ class Adminer {
 
 	/** Print list of indexes on table in tabular format
 	* @param Index[] $indexes data about all indexes on a table
-	* @return void
 	*/
-	function tableIndexesPrint(array $indexes) {
+	function tableIndexesPrint(array $indexes): void {
 		echo "<table>\n";
 		foreach ($indexes as $name => $index) {
 			ksort($index["columns"]); // enforce correct columns order
@@ -365,9 +352,8 @@ class Adminer {
 	/** Print columns box in select
 	* @param list<string> $select result of selectColumnsProcess()[0]
 	* @param string[] $columns selectable columns
-	* @return void
 	*/
-	function selectColumnsPrint(array $select, array $columns) {
+	function selectColumnsPrint(array $select, array $columns): void {
 		global $driver;
 		print_fieldset("select", lang('Select'), $select);
 		$i = 0;
@@ -393,9 +379,8 @@ class Adminer {
 	* @param list<string> $where result of selectSearchProcess()
 	* @param string[] $columns selectable columns
 	* @param Index[] $indexes
-	* @return void
 	*/
-	function selectSearchPrint(array $where, array $columns, array $indexes) {
+	function selectSearchPrint(array $where, array $columns, array $indexes): void {
 		print_fieldset("search", lang('Search'), $where);
 		foreach ($indexes as $i => $index) {
 			if ($index["type"] == "FULLTEXT") {
@@ -429,9 +414,8 @@ class Adminer {
 	* @param list<string> $order result of selectOrderProcess()
 	* @param string[] $columns selectable columns
 	* @param Index[] $indexes
-	* @return void
 	*/
-	function selectOrderPrint(array $order, array $columns, array $indexes) {
+	function selectOrderPrint(array $order, array $columns, array $indexes): void {
 		print_fieldset("sort", lang('Sort'), $order);
 		$i = 0;
 		foreach ((array) $_GET["order"] as $key => $val) {
@@ -448,9 +432,8 @@ class Adminer {
 
 	/** Print limit box in select
 	* @param string $limit result of selectLimitProcess()
-	* @return void
 	*/
-	function selectLimitPrint(string $limit) {
+	function selectLimitPrint(string $limit): void {
 		echo "<fieldset><legend>" . lang('Limit') . "</legend><div>"; // <div> for easy styling
 		echo "<input type='number' name='limit' class='size' value='" . h($limit) . "'>";
 		echo script("qsl('input').oninput = selectFieldChange;", "");
@@ -459,9 +442,8 @@ class Adminer {
 
 	/** Print text length box in select
 	* @param string $text_length result of selectLengthProcess()
-	* @return void
 	*/
-	function selectLengthPrint(string $text_length) {
+	function selectLengthPrint(string $text_length): void {
 		if ($text_length !== null) {
 			echo "<fieldset><legend>" . lang('Text length') . "</legend><div>";
 			echo "<input type='number' name='text_length' class='size' value='" . h($text_length) . "'>";
@@ -471,9 +453,8 @@ class Adminer {
 
 	/** Print action box in select
 	* @param Index[] $indexes
-	* @return void
 	*/
-	function selectActionPrint(array $indexes) {
+	function selectActionPrint(array $indexes): void {
 		echo "<fieldset><legend>" . lang('Action') . "</legend><div>";
 		echo "<input type='submit' value='" . lang('Select') . "'>";
 		echo " <span id='noindex' title='" . lang('Full table scan') . "'></span>";
@@ -499,23 +480,22 @@ class Adminer {
 	/** Print command box in select
 	* @return bool whether to print default commands
 	*/
-	function selectCommandPrint() {
+	function selectCommandPrint(): bool {
 		return !information_schema(DB);
 	}
 
 	/** Print import box in select
 	* @return bool whether to print default import
 	*/
-	function selectImportPrint() {
+	function selectImportPrint(): bool {
 		return !information_schema(DB);
 	}
 
 	/** Print extra text in the end of a select form
 	* @param string[] $emailFields fields holding e-mails
 	* @param string[] $columns selectable columns
-	* @return void
 	*/
-	function selectEmailPrint(array $emailFields, array $columns) {
+	function selectEmailPrint(array $emailFields, array $columns): void {
 	}
 
 	/** Process columns box in select
@@ -523,7 +503,7 @@ class Adminer {
 	* @param Index[] $indexes
 	* @return list<list<string>> [[select_expressions], [group_expressions]]
 	*/
-	function selectColumnsProcess(array $columns, array $indexes) {
+	function selectColumnsProcess(array $columns, array $indexes): array {
 		global $driver;
 		$select = array(); // select expressions, empty for *
 		$group = array(); // expressions without aggregation - will be used for GROUP BY if an aggregation function is used
@@ -543,7 +523,7 @@ class Adminer {
 	* @param Index[] $indexes
 	* @return list<string> expressions to join by AND
 	*/
-	function selectSearchProcess(array $fields, array $indexes) {
+	function selectSearchProcess(array $fields, array $indexes): array {
 		global $connection, $driver;
 		$return = array();
 		foreach ($indexes as $i => $index) {
@@ -597,7 +577,7 @@ class Adminer {
 	* @param Index[] $indexes
 	* @return list<string> expressions to join by comma
 	*/
-	function selectOrderProcess(array $fields, array $indexes) {
+	function selectOrderProcess(array $fields, array $indexes): array {
 		$return = array();
 		foreach ((array) $_GET["order"] as $key => $val) {
 			if ($val != "") {
@@ -612,14 +592,14 @@ class Adminer {
 	/** Process limit box in select
 	* @return string expression to use in LIMIT, will be escaped
 	*/
-	function selectLimitProcess() {
+	function selectLimitProcess(): string {
 		return (isset($_GET["limit"]) ? $_GET["limit"] : "50");
 	}
 
 	/** Process length box in select
 	* @return string number of characters to shorten texts, will be escaped
 	*/
-	function selectLengthProcess() {
+	function selectLengthProcess(): string {
 		return (isset($_GET["text_length"]) ? $_GET["text_length"] : "100");
 	}
 
@@ -628,7 +608,7 @@ class Adminer {
 	* @param ForeignKey[] $foreignKeys
 	* @return bool true if processed, false to process other parts of form
 	*/
-	function selectEmailProcess(array $where, array $foreignKeys) {
+	function selectEmailProcess(array $where, array $foreignKeys): bool {
 		return false;
 	}
 
@@ -641,16 +621,15 @@ class Adminer {
 	* @param int $page index of page starting at zero
 	* @return string empty string to use default query
 	*/
-	function selectQueryBuild(array $select, array $where, array $group, array $order, int $limit, int $page) {
+	function selectQueryBuild(array $select, array $where, array $group, array $order, int $limit, int $page): string {
 		return "";
 	}
 
 	/** Query printed after execution in the message
 	* @param string $query executed query
 	* @param string $time elapsed time
-	* @return string
 	*/
-	function messageQuery(string $query, string $time, bool $failed = false) {
+	function messageQuery(string $query, string $time, bool $failed = false): string {
 		global $driver;
 		restart_session();
 		$history = &get_session("queries");
@@ -678,16 +657,15 @@ class Adminer {
 	/** Print before edit form
 	* @param Field[] $fields
 	* @param mixed $row
-	* @return void
 	*/
-	function editRowPrint(string $table, array $fields, $row, bool $update) {
+	function editRowPrint(string $table, array $fields, $row, bool $update): void {
 	}
 
 	/** Functions displayed in edit form
 	* @param Field $field single field from fields()
 	* @return list<string>
 	*/
-	function editFunctions(array $field) {
+	function editFunctions(array $field): array {
 		global $driver;
 		$return = ($field["null"] ? "NULL/" : "");
 		$update = isset($_GET["select"]) || where($_GET);
@@ -715,7 +693,7 @@ class Adminer {
 	* @param string $attrs attributes to use inside the tag
 	* @return string custom input field or empty string for default
 	*/
-	function editInput(string $table, array $field, string $attrs, string $value) {
+	function editInput(string $table, array $field, string $attrs, string $value): string {
 		if ($field["type"] == "enum") {
 			return (isset($_GET["select"]) ? "<label><input type='radio'$attrs value='-1' checked><i>" . lang('original') . "</i></label> " : "")
 				. ($field["null"] ? "<label><input type='radio'$attrs value=''" . ($value !== null || isset($_GET["select"]) ? "" : " checked") . "><i>NULL</i></label> " : "")
@@ -728,9 +706,8 @@ class Adminer {
 	/** Get hint for edit field
 	* @param string $table table name
 	* @param Field $field single field from fields()
-	* @return string
 	*/
-	function editHint(string $table, array $field, string $value) {
+	function editHint(string $table, array $field, string $value): string {
 		return "";
 	}
 
@@ -738,7 +715,7 @@ class Adminer {
 	* @param Field $field single field from fields()
 	* @return string expression to use in a query
 	*/
-	function processInput(array $field, string $value, string $function = "") {
+	function processInput(array $field, string $value, string $function = ""): string {
 		if ($function == "SQL") {
 			return $value; // SQL injection
 		}
@@ -763,7 +740,7 @@ class Adminer {
 	/** Return export output options
 	* @return string[]
 	*/
-	function dumpOutput() {
+	function dumpOutput(): array {
 		$return = array('text' => lang('open'), 'file' => lang('save'));
 		if (function_exists('gzencode')) {
 			$return['gz'] = 'gzip';
@@ -774,21 +751,21 @@ class Adminer {
 	/** Return export format options
 	* @return string[] empty to disable export
 	*/
-	function dumpFormat() {
+	function dumpFormat(): array {
 		return (support("dump") ? array('sql' => 'SQL') : array()) + array('csv' => 'CSV,', 'csv;' => 'CSV;', 'tsv' => 'TSV');
 	}
 
 	/** Export database structure
 	* @return void prints data
 	*/
-	function dumpDatabase(string $db) {
+	function dumpDatabase(string $db): void {
 	}
 
 	/** Export table structure
 	* @param int $is_view 0 table, 1 view, 2 temporary view table
 	* @return void prints data
 	*/
-	function dumpTable(string $table, string $style, int $is_view = 0) {
+	function dumpTable(string $table, string $style, int $is_view = 0): void {
 		if ($_POST["format"] != "sql") {
 			echo "\xef\xbb\xbf"; // UTF-8 byte order mark
 			if ($style) {
@@ -820,7 +797,7 @@ class Adminer {
 	/** Export table data
 	* @return void prints data
 	*/
-	function dumpData(string $table, string $style, string $query) {
+	function dumpData(string $table, string $style, string $query): void {
 		global $connection;
 		if ($style) {
 			$max_packet = (JUSH == "sqlite" ? 0 : 1048576); // default, minimum is 1024
@@ -911,14 +888,14 @@ class Adminer {
 	/** Set export filename
 	* @return string filename without extension
 	*/
-	function dumpFilename(string $identifier) {
+	function dumpFilename(string $identifier): string {
 		return friendly_url($identifier != "" ? $identifier : (SERVER != "" ? SERVER : "localhost"));
 	}
 
 	/** Send headers for export
 	* @return string extension
 	*/
-	function dumpHeaders(string $identifier, bool $multi_table = false) {
+	function dumpHeaders(string $identifier, bool $multi_table = false): string {
 		$output = $_POST["output"];
 		$ext = (preg_match('~sql~', $_POST["format"]) ? "sql" : ($multi_table ? "tar" : "csv")); // multiple CSV packed to TAR
 		header("Content-Type: " .
@@ -938,7 +915,7 @@ class Adminer {
 	/** Print text after export
 	* @return void prints data
 	*/
-	function dumpFooter() {
+	function dumpFooter(): void {
 		if ($_POST["format"] == "sql") {
 			echo "-- " . gmdate("Y-m-d H:i:s e") . "\n";
 		}
@@ -947,14 +924,14 @@ class Adminer {
 	/** Set the path of the file for webserver load
 	* @return string path of the sql dump file
 	*/
-	function importServerPath() {
+	function importServerPath(): string {
 		return "adminer.sql";
 	}
 
 	/** Print homepage
 	* @return bool whether to print default homepage
 	*/
-	function homepage() {
+	function homepage(): bool {
 		echo '<p class="links">' . ($_GET["ns"] == "" && support("database") ? '<a href="' . h(ME) . 'database=">' . lang('Alter database') . "</a>\n" : "");
 		echo (support("scheme") ? "<a href='" . h(ME) . "scheme='>" . ($_GET["ns"] != "" ? lang('Alter schema') : lang('Create schema')) . "</a>\n" : "");
 		echo ($_GET["ns"] !== "" ? '<a href="' . h(ME) . 'schema=">' . lang('Database schema') . "</a>\n" : "");
@@ -964,9 +941,8 @@ class Adminer {
 
 	/** Print navigation after Adminer title
 	* @param string $missing can be "auth" if there is no database connection, "db" if there is no database selected, "ns" with invalid schema
-	* @return void
 	*/
-	function navigation(string $missing) {
+	function navigation(string $missing): void {
 		global $VERSION, $drivers, $connection;
 		echo "<h1>" . $this->name() . " <span class='version'>$VERSION";
 		$new_version = $_COOKIE["adminer_version"];
@@ -1025,9 +1001,8 @@ class Adminer {
 
 	/** Set up syntax highlight for code and <textarea>
 	* @param TableStatus[] $tables result of table_status('', true)
-	* @return void
 	*/
-	function syntaxHighlighting(array $tables) {
+	function syntaxHighlighting(array $tables): void {
 		global $connection;
 		// this is matched by compile.php
 		echo script_src("../externals/jush/modules/jush.js");
@@ -1055,9 +1030,8 @@ class Adminer {
 	}
 
 	/** Print databases list in menu
-	* @return void
 	*/
-	function databasesPrint(string $missing) {
+	function databasesPrint(string $missing): void {
 		global $adminer, $connection;
 		$databases = $this->databases();
 		if (DB && $databases && !in_array(DB, $databases)) {
@@ -1090,9 +1064,8 @@ class Adminer {
 
 	/** Print table list in menu
 	* @param TableStatus[] $tables result of table_status('', true)
-	* @return void
 	*/
-	function tablesPrint(array $tables) {
+	function tablesPrint(array $tables): void {
 		echo "<ul id='tables'>" . script("mixin(qs('#tables'), {onmouseover: menuOver, onmouseout: menuOut});");
 		foreach ($tables as $table => $status) {
 			$name = $this->tableName($status);
diff --git a/adminer/include/auth.inc.php b/adminer/include/auth.inc.php
index dab95da1..903248fc 100644
--- a/adminer/include/auth.inc.php
+++ b/adminer/include/auth.inc.php
@@ -17,8 +17,7 @@ if ($_COOKIE["adminer_permanent"]) {
 	}
 }
 
-/** @return void */
-function add_invalid_login() {
+function add_invalid_login(): void {
 	global $adminer;
 	$base = get_temp_dir() . "/adminer.invalid";
 	// adminer.invalid may not be writable by us, try the files with random suffixes
@@ -51,8 +50,7 @@ function add_invalid_login() {
 	file_write_unlock($fp, serialize($invalids));
 }
 
-/** @return void */
-function check_invalid_login() {
+function check_invalid_login(): void {
 	global $adminer;
 	$invalids = array();
 	foreach (glob(get_temp_dir() . "/adminer.invalid*") as $filename) {
@@ -115,8 +113,7 @@ if ($auth) {
 	}
 }
 
-/** @return void */
-function unset_permanent() {
+function unset_permanent(): void {
 	global $permanent;
 	foreach ($permanent as $key => $val) {
 		list($vendor, $server, $username, $db) = array_map('base64_decode', explode("-", $key));
diff --git a/adminer/include/coverage.inc.php b/adminer/include/coverage.inc.php
index 990a2c4f..e6a9c42e 100644
--- a/adminer/include/coverage.inc.php
+++ b/adminer/include/coverage.inc.php
@@ -3,8 +3,7 @@ namespace Adminer;
 
 // coverage is used in tests and removed in compilation
 if (extension_loaded("xdebug") && file_exists(sys_get_temp_dir() . "/adminer.coverage")) {
-	/** @return void */
-	function save_coverage() {
+	function save_coverage(): void {
 		$coverage_filename = sys_get_temp_dir() . "/adminer.coverage";
 		$coverage = unserialize(file_get_contents($coverage_filename));
 		foreach (xdebug_get_code_coverage() as $filename => $lines) {
diff --git a/adminer/include/db.inc.php b/adminer/include/db.inc.php
index 5e3c6177..be588c2b 100644
--- a/adminer/include/db.inc.php
+++ b/adminer/include/db.inc.php
@@ -14,19 +14,17 @@ abstract class SqlDb {
 	/** @var Result|bool */ protected $multi; // used for multiquery
 
 	/** Connect to server
-	* @return bool
 	*/
-	abstract function connect(string $server, string $username, string $password);
+	abstract function connect(string $server, string $username, string $password): bool;
 
 	/** Quote string to use in SQL
 	* @return string escaped string enclosed in '
 	*/
-	abstract function quote(string $string);
+	abstract function quote(string $string): string;
 
 	/** Select database
-	* @return bool
 	*/
-	abstract function select_db(string $database);
+	abstract function select_db(string $database): bool;
 
 	/** Send query
 	* @return Result|bool
@@ -48,9 +46,8 @@ abstract class SqlDb {
 	}
 
 	/** Fetch next resultset
-	* @return bool
 	*/
-	function next_result() {
+	function next_result(): bool {
 		return false;
 	}
 
diff --git a/adminer/include/design.inc.php b/adminer/include/design.inc.php
index 07f9766c..d5ce1174 100644
--- a/adminer/include/design.inc.php
+++ b/adminer/include/design.inc.php
@@ -5,9 +5,8 @@ namespace Adminer;
 * @param string $title used in title, breadcrumb and heading, should be HTML escaped
 * @param mixed $breadcrumb ["key" => "link", "key2" => ["link", "desc"]], null for nothing, false for driver only, true for driver and server
 * @param string $title2 used after colon in title and heading, should be HTML escaped
-* @return void
 */
-function page_header(string $title, string $error = "", $breadcrumb = array(), string $title2 = "") {
+function page_header(string $title, string $error = "", $breadcrumb = array(), string $title2 = ""): void {
 	global $LANG, $VERSION, $adminer, $drivers;
 	page_headers();
 	if (is_ajax() && $error) {
@@ -127,9 +126,8 @@ const thousandsSeparator = '" . js_escape(lang(',')) . "';")
 }
 
 /** Send HTTP headers
-* @return void
 */
-function page_headers() {
+function page_headers(): void {
 	global $adminer;
 	header("Content-Type: text/html; charset=utf-8");
 	header("Cache-Control: no-cache");
@@ -150,7 +148,7 @@ function page_headers() {
 /** Get Content Security Policy headers
 * @return list<string[]> of arrays with directive name in key, allowed sources in value
 */
-function csp() {
+function csp(): array {
 	return array(
 		array(
 			"script-src" => "'self' 'unsafe-inline' 'nonce-" . get_nonce() . "' 'strict-dynamic'", // 'self' is a fallback for browsers not supporting 'strict-dynamic', 'unsafe-inline' is a fallback for browsers not supporting 'nonce-'
@@ -166,7 +164,7 @@ function csp() {
 /** Get a CSP nonce
 * @return string Base64 value
 */
-function get_nonce() {
+function get_nonce(): string {
 	static $nonce;
 	if (!$nonce) {
 		$nonce = base64_encode(rand_string());
@@ -175,9 +173,8 @@ function get_nonce() {
 }
 
 /** Print flash and error messages
-* @return void
 */
-function page_messages(string $error) {
+function page_messages(string $error): void {
 	global $adminer;
 	$uri = preg_replace('~^[^?]*~', '', $_SERVER["REQUEST_URI"]);
 	$messages = idx($_SESSION["messages"], $uri);
@@ -195,9 +192,8 @@ function page_messages(string $error) {
 
 /** Print HTML footer
 * @param string $missing "auth", "db", "ns"
-* @return void
 */
-function page_footer(string $missing = "") {
+function page_footer(string $missing = ""): void {
 	global $adminer;
 	echo "</div>\n\n<div id='menu'>\n";
 	$adminer->navigation($missing);
diff --git a/adminer/include/driver.inc.php b/adminer/include/driver.inc.php
index a15a6858..0a04d937 100644
--- a/adminer/include/driver.inc.php
+++ b/adminer/include/driver.inc.php
@@ -4,17 +4,15 @@ namespace Adminer;
 $drivers = array();
 
 /** Add a driver
-* @return void
 */
-function add_driver(string $id, string $name) {
+function add_driver(string $id, string $name): void {
 	global $drivers;
 	$drivers[$id] = $name;
 }
 
 /** Get driver name
-* @return string
 */
-function get_driver(string $id) {
+function get_driver(string $id): string {
 	global $drivers;
 	return $drivers[$id];
 }
@@ -44,7 +42,7 @@ abstract class SqlDriver {
 	/** Get all types
 	* @return int[] [$type => $maximum_unsigned_length, ...]
 	*/
-	function types() {
+	function types(): array {
 		return call_user_func_array('array_merge', array_values($this->types));
 	}
 
@@ -137,9 +135,8 @@ abstract class SqlDriver {
 	}
 
 	/** Get RETURNING clause for INSERT queries (PostgreSQL specific)
-	* @return string
 	*/
-	function insertReturning(string $table) {
+	function insertReturning(string $table): string {
 		return "";
 	}
 
@@ -184,24 +181,21 @@ abstract class SqlDriver {
 	* @param string $idf escaped column name
 	* @param array{op:string, val:string} $val
 	* @param Field $field
-	* @return string
 	*/
-	function convertSearch(string $idf, array $val, array $field) {
+	function convertSearch(string $idf, array $val, array $field): string {
 		return $idf;
 	}
 
 	/** Convert operator so it can be used in search
-	* @return string
 	*/
-	function convertOperator(string $operator) {
+	function convertOperator(string $operator): string {
 		return $operator;
 	}
 
 	/** Convert value returned by database to actual value
 	* @param Field $field
-	* @return string
 	*/
-	function value(string $val, array $field) {
+	function value(string $val, array $field): string {
 		return (method_exists($this->conn, 'value')
 			? $this->conn->value($val, $field)
 			: (is_resource($val) ? stream_get_contents($val) : $val)
@@ -209,9 +203,8 @@ abstract class SqlDriver {
 	}
 
 	/** Quote binary string
-	* @return string
 	*/
-	function quoteBinary(string $s) {
+	function quoteBinary(string $s): string {
 		return q($s);
 	}
 
@@ -228,31 +221,29 @@ abstract class SqlDriver {
 	}
 
 	/** Check if C-style escapes are supported
-	* @return bool
 	*/
-	function hasCStyleEscapes() {
+	function hasCStyleEscapes(): bool {
 		return false;
 	}
 
 	/** Get supported engines
 	* @return list<string>
 	*/
-	function engines() {
+	function engines(): array {
 		return array();
 	}
 
 	/** Check whether table supports indexes
 	* @param TableStatus $table_status result of table_status1()
-	* @return bool
 	*/
-	function supportsIndex(array $table_status) {
+	function supportsIndex(array $table_status): bool {
 		return !is_view($table_status);
 	}
 
 	/** Get defined check constraints
 	* @return string[] [$name => $clause]
 	*/
-	function checkConstraints(string $table) {
+	function checkConstraints(string $table): array {
 		// MariaDB contains CHECK_CONSTRAINTS.TABLE_NAME, MySQL and PostrgreSQL not
 		return get_key_vals("SELECT c.CONSTRAINT_NAME, CHECK_CLAUSE
 FROM INFORMATION_SCHEMA.CHECK_CONSTRAINTS c
diff --git a/adminer/include/editing.inc.php b/adminer/include/editing.inc.php
index a65c85e5..d58afaf1 100644
--- a/adminer/include/editing.inc.php
+++ b/adminer/include/editing.inc.php
@@ -9,7 +9,7 @@ namespace Adminer;
 * @param string[] $orgtables
 * @return string[] $orgtables
 */
-function select($result, Db $connection2 = null, array $orgtables = array(), int $limit = 0) {
+function select($result, Db $connection2 = null, array $orgtables = array(), int $limit = 0): array {
 	$links = array(); // colno => orgtable - create links from these columns
 	$indexes = array(); // orgtable => array(column => colno) - primary keys
 	$columns = array(); // orgtable => array(column => ) - not selected columns in primary key
@@ -102,7 +102,7 @@ function select($result, Db $connection2 = null, array $orgtables = array(), int
 /** Get referencable tables with single column primary key except self
 * @return array<string, Field> [$table_name => $field]
 */
-function referencable_primary(string $self) {
+function referencable_primary(string $self): array {
 	$return = array(); // table_name => field
 	foreach (table_status('', true) as $table_name => $table) {
 		if ($table_name != $self && fk_support($table)) {
@@ -122,9 +122,8 @@ function referencable_primary(string $self) {
 
 /** Print SQL <textarea> tag
 * @param string|list<array{string}> $value
-* @return void
 */
-function textarea(string $name, $value, int $rows = 10, int $cols = 80) {
+function textarea(string $name, $value, int $rows = 10, int $cols = 80): void {
 	echo "<textarea name='" . h($name) . "' rows='$rows' cols='$cols' class='sqlarea jush-" . JUSH . "' spellcheck='false' wrap='off'>";
 	if (is_array($value)) {
 		foreach ($value as $val) { // not implode() to save memory
@@ -138,9 +137,8 @@ function textarea(string $name, $value, int $rows = 10, int $cols = 80) {
 
 /** Generate HTML <select> or <input> if $options are empty
 * @param string[] $options
-* @return string
 */
-function select_input(string $attrs, array $options, string $value = "", string $onchange = "", string $placeholder = "") {
+function select_input(string $attrs, array $options, string $value = "", string $onchange = "", string $placeholder = ""): string {
 	$tag = ($options ? "select" : "input");
 	return "<$tag$attrs" . ($options
 		? "><option value=''>$placeholder" . optionlist($options, $value, true) . "</select>"
@@ -151,9 +149,8 @@ function select_input(string $attrs, array $options, string $value = "", string
 /** Print one row in JSON object
 * @param string $key or "" to close the object
 * @param string|int $val
-* @return void
 */
-function json_row(string $key, $val = null) {
+function json_row(string $key, $val = null): void {
 	static $first = true;
 	if ($first) {
 		echo "{";
@@ -172,9 +169,8 @@ function json_row(string $key, $val = null) {
 * @param list<string> $collations
 * @param string[] $foreign_keys
 * @param list<string> $extra_types extra types to prepend
-* @return void
 */
-function edit_type(string $key, array $field, array $collations, array $foreign_keys = array(), array $extra_types = array()) {
+function edit_type(string $key, array $field, array $collations, array $foreign_keys = array(), array $extra_types = array()): void {
 	global $driver;
 	$type = $field["type"];
 	echo "<td><select name='" . h($key) . "[type]' class='type' aria-labelledby='label-type'>";
@@ -209,7 +205,7 @@ function edit_type(string $key, array $field, array $collations, array $foreign_
 /** Get partition info
 * @return array{partition_by:string, partition:string, partitions:string, partition_names:list<string>, partition_values:list<string>}
 */
-function get_partitions_info(string $table) {
+function get_partitions_info(string $table): array {
 	global $connection;
 	$from = "FROM information_schema.PARTITIONS WHERE TABLE_SCHEMA = " . q(DB) . " AND TABLE_NAME = " . q($table);
 	$result = $connection->query("SELECT PARTITION_METHOD, PARTITION_EXPRESSION, PARTITION_ORDINAL_POSITION $from ORDER BY PARTITION_ORDINAL_POSITION DESC LIMIT 1");
@@ -222,9 +218,8 @@ function get_partitions_info(string $table) {
 }
 
 /** Filter length value including enums
-* @return string
 */
-function process_length(string $length) {
+function process_length(string $length): string {
 	global $driver;
 	$enum_length = $driver->enumLength;
 	return (preg_match("~^\\s*\\(?\\s*$enum_length(?:\\s*,\\s*$enum_length)*+\\s*\\)?\\s*\$~", $length) && preg_match_all("~$enum_length~", $length, $matches)
@@ -235,9 +230,8 @@ function process_length(string $length) {
 
 /** Create SQL string from field type
 * @param FieldType $field
-* @return string
 */
-function process_type(array $field, string $collate = "COLLATE") {
+function process_type(array $field, string $collate = "COLLATE"): string {
 	global $driver;
 	return " $field[type]"
 		. process_length($field["length"])
@@ -251,7 +245,7 @@ function process_type(array $field, string $collate = "COLLATE") {
 * @param Field $type_field information about field type
 * @return list<string> ["field", "type", "NULL", "DEFAULT", "ON UPDATE", "COMMENT", "AUTO_INCREMENT"]
 */
-function process_field(array $field, array $type_field) {
+function process_field(array $field, array $type_field): array {
 	// MariaDB exports CURRENT_TIMESTAMP as a function.
 	if ($field["on_update"]) {
 		$field["on_update"] = str_ireplace("current_timestamp()", "CURRENT_TIMESTAMP", $field["on_update"]);
@@ -269,9 +263,8 @@ function process_field(array $field, array $type_field) {
 
 /** Get default value clause
 * @param Field $field
-* @return string
 */
-function default_value(array $field) {
+function default_value(array $field): string {
 	global $driver;
 	$default = $field["default"];
 	$generated = $field["generated"];
@@ -307,9 +300,8 @@ function type_class(string $type) {
 * @param list<string> $collations
 * @param 'TABLE'|'PROCEDURE' $type
 * @param string[] $foreign_keys
-* @return void
 */
-function edit_fields(array $fields, array $collations, $type = "TABLE", array $foreign_keys = array()) {
+function edit_fields(array $fields, array $collations, $type = "TABLE", array $foreign_keys = array()): void {
 	global $driver;
 	$fields = array_values($fields);
 	$default_class = (($_POST ? $_POST["defaults"] : get_setting("defaults")) ? "" : " class='hidden'");
@@ -369,9 +361,8 @@ function edit_fields(array $fields, array $collations, $type = "TABLE", array $f
 
 /** Move fields up and down or add field
 * @param Field[] $fields
-* @return bool
 */
-function process_fields(&array $fields) {
+function process_fields(&array $fields): bool {
 	$offset = 0;
 	if ($_POST["up"]) {
 		$last = 0;
@@ -410,9 +401,8 @@ function process_fields(&array $fields) {
 
 /** Callback used in routine()
 * @param list<string> $match
-* @return string
 */
-function normalize_enum(array $match) {
+function normalize_enum(array $match): string {
 	$val = $match[0];
 	return "'" . str_replace("'", "''", addcslashes(stripcslashes(str_replace($val[0] . $val[0], $val[0], substr($val, 1, -1))), '\\')) . "'";
 }
@@ -444,7 +434,7 @@ function grant(string $grant, array $privileges, string $columns, string $on) {
 * @param string $drop_test drop test object query
 * @return void redirect on success
 */
-function drop_create(string $drop, string $create, string $drop_created, string $test, string $drop_test, string $location, string $message_drop, string $message_alter, string $message_create, string $old_name, string $new_name) {
+function drop_create(string $drop, string $create, string $drop_created, string $test, string $drop_test, string $location, string $message_drop, string $message_alter, string $message_create, string $old_name, string $new_name): void {
 	if ($_POST["drop"]) {
 		query_redirect($drop, $location, $message_drop);
 	} elseif ($old_name == "") {
@@ -466,9 +456,8 @@ function drop_create(string $drop, string $create, string $drop_created, string
 
 /** Generate SQL query for creating trigger
 * @param Trigger $row result of trigger()
-* @return string
 */
-function create_trigger(string $on, array $row) {
+function create_trigger(string $on, array $row): string {
 	$timing_event = " $row[Timing] $row[Event]" . (preg_match('~ OF~', $row["Event"]) ? " $row[Of]" : ""); // SQL injection
 	return "CREATE TRIGGER "
 		. idf_escape($row["Trigger"])
@@ -481,9 +470,8 @@ function create_trigger(string $on, array $row) {
 /** Generate SQL query for creating routine
 * @param 'PROCEDURE'|'FUNCTION' $routine
 * @param Routine $row result of routine()
-* @return string
 */
-function create_routine($routine, array $row) {
+function create_routine($routine, array $row): string {
 	global $driver;
 	$set = array();
 	$fields = (array) $row["fields"];
@@ -504,17 +492,15 @@ function create_routine($routine, array $row) {
 }
 
 /** Remove current user definer from SQL command
-* @return string
 */
-function remove_definer(string $query) {
+function remove_definer(string $query): string {
 	return preg_replace('~^([A-Z =]+) DEFINER=`' . preg_replace('~@(.*)~', '`@`(%|\1)', logged_user()) . '`~', '\1', $query); //! proper escaping of user
 }
 
 /** Format foreign key to use in SQL query
 * @param ForeignKey $foreign_key
-* @return string
 */
-function format_foreign_key(array $foreign_key) {
+function format_foreign_key(array $foreign_key): string {
 	global $driver;
 	$db = $foreign_key["db"];
 	$ns = $foreign_key["ns"];
@@ -532,7 +518,7 @@ function format_foreign_key(array $foreign_key) {
 * @param TmpFile $tmp_file
 * @return void prints the output
 */
-function tar_file(string $filename, $tmp_file) {
+function tar_file(string $filename, $tmp_file): void {
 	$return = pack("a100a8a8a8a12a12", $filename, 644, 0, 0, decoct($tmp_file->size), decoct(time()));
 	$checksum = 8*32; // space for checksum itself
 	for ($i=0; $i < strlen($return); $i++) {
@@ -546,9 +532,8 @@ function tar_file(string $filename, $tmp_file) {
 }
 
 /** Get INI bytes value
-* @return int
 */
-function ini_bytes(string $ini) {
+function ini_bytes(string $ini): int {
 	$val = ini_get($ini);
 	switch (strtolower(substr($val, -1))) {
 		case 'g':
@@ -566,7 +551,7 @@ function ini_bytes(string $ini) {
 * @param string $text HTML code
 * @return string HTML code
 */
-function doc_link(array $paths, string $text = "<sup>?</sup>") {
+function doc_link(array $paths, string $text = "<sup>?</sup>"): string {
 	global $connection;
 	$server_info = $connection->server_info;
 	$version = preg_replace('~^(\d\.?\d).*~s', '\1', $server_info); // two most significant digits
@@ -587,7 +572,7 @@ function doc_link(array $paths, string $text = "<sup>?</sup>") {
 /** Compute size of database
 * @return string formatted
 */
-function db_size(string $db) {
+function db_size(string $db): string {
 	global $connection;
 	if (!$connection->select_db($db)) {
 		return "?";
@@ -600,9 +585,8 @@ function db_size(string $db) {
 }
 
 /** Print SET NAMES if utf8mb4 might be needed
-* @return void
 */
-function set_utf8mb4(string $create) {
+function set_utf8mb4(string $create): void {
 	global $connection;
 	static $set = false;
 	if (!$set && preg_match('~\butf8mb4~i', $create)) { // possible false positive
diff --git a/adminer/include/functions.inc.php b/adminer/include/functions.inc.php
index 5a509b7d..55ed3ae2 100644
--- a/adminer/include/functions.inc.php
+++ b/adminer/include/functions.inc.php
@@ -4,9 +4,8 @@ namespace Adminer;
 // This file is used both in Adminer and Adminer Editor.
 
 /** Get database connection
-* @return Db
 */
-function connection() {
+function connection(): Db {
 	// can be used in customization, $connection is minified
 	global $connection;
 	return $connection;
@@ -29,18 +28,16 @@ function driver() {
 }
 
 /** Get Adminer version
-* @return string
 */
-function version() {
+function version(): string {
 	global $VERSION;
 	return $VERSION;
 }
 
 /** Unescape database identifier
 * @param string $idf text inside ``
-* @return string
 */
-function idf_unescape(string $idf) {
+function idf_unescape(string $idf): string {
 	if (!preg_match('~^[`\'"[]~', $idf)) {
 		return $idf;
 	}
@@ -49,17 +46,15 @@ function idf_unescape(string $idf) {
 }
 
 /** Shortcut for $connection->quote($string)
-* @return string
 */
-function q(string $string) {
+function q(string $string): string {
 	global $connection;
 	return $connection->quote($string);
 }
 
 /** Escape string to use inside ''
-* @return string
 */
-function escape_string(string $val) {
+function escape_string(string $val): string {
 	return substr(q($val), 1, -1);
 }
 
@@ -75,16 +70,14 @@ function idx(?array $array, $key, $default = null) {
 }
 
 /** Remove non-digits from a string
-* @return string
 */
-function number(string $val) {
+function number(string $val): string {
 	return preg_replace('~[^0-9]+~', '', $val);
 }
 
 /** Get regular expression to match numeric types
-* @return string
 */
-function number_type() {
+function number_type(): string {
 	return '((?<!o)int(?!er)|numeric|real|float|double|decimal|money)'; // not point, not interval
 }
 
@@ -93,7 +86,7 @@ function number_type() {
 * @param bool $filter whether to leave values as is
 * @return void modified in place
 */
-function remove_slashes(array $process, bool $filter = false) {
+function remove_slashes(array $process, bool $filter = false): void {
 	if (function_exists("get_magic_quotes_gpc") && get_magic_quotes_gpc()) {
 		while (list($key, $val) = each($process)) {
 			foreach ($val as $k => $v) {
@@ -110,9 +103,8 @@ function remove_slashes(array $process, bool $filter = false) {
 }
 
 /** Escape or unescape string to use inside form []
-* @return string
 */
-function bracket_escape(string $idf, bool $back = false) {
+function bracket_escape(string $idf, bool $back = false): string {
 	// escape brackets inside name="x[]"
 	static $trans = array(':' => ':1', ']' => ':2', '[' => ':3', '"' => ':4');
 	return strtr($idf, ($back ? array_flip($trans) : $trans));
@@ -122,9 +114,8 @@ function bracket_escape(string $idf, bool $back = false) {
 * @param string|float $version required version
 * @param string|float $maria_db required MariaDB version
 * @param Db $connection2 defaults to $connection
-* @return bool
 */
-function min_version($version, $maria_db = "", Db $connection2 = null) {
+function min_version($version, $maria_db = "", Db $connection2 = null): bool {
 	global $connection;
 	if (!$connection2) {
 		$connection2 = $connection;
@@ -138,24 +129,21 @@ function min_version($version, $maria_db = "", Db $connection2 = null) {
 }
 
 /** Get connection charset
-* @return string
 */
-function charset(Db $connection) {
+function charset(Db $connection): string {
 	return (min_version("5.5.3", 0, $connection) ? "utf8mb4" : "utf8"); // SHOW CHARSET would require an extra query
 }
 
 /** Get INI boolean value
-* @return bool
 */
-function ini_bool(string $ini) {
+function ini_bool(string $ini): bool {
 	$val = ini_get($ini);
 	return (preg_match('~^(on|true|yes)$~i', $val) || (int) $val); // boolean values set by php_value are strings
 }
 
 /** Check if SID is necessary
-* @return bool
 */
-function sid() {
+function sid(): bool {
 	static $return;
 	if ($return === null) { // restart_session() defines SID
 		$return = (SID && !($_COOKIE && ini_bool("session.use_cookies"))); // $_COOKIE - don't pass SID with permanent login
@@ -164,9 +152,8 @@ function sid() {
 }
 
 /** Set password to session
-* @return void
 */
-function set_password(string $vendor, string $server, string $username, ?string $password) {
+function set_password(string $vendor, string $server, string $username, ?string $password): void {
 	$_SESSION["pwds"][$vendor][$server][$username] = ($_COOKIE["adminer_key"] && is_string($password)
 		? array(encrypt_string($password, $_COOKIE["adminer_key"]))
 		: $password
@@ -190,7 +177,7 @@ function get_password() {
 /** Get single value from database
 * @return string or false if error
 */
-function get_val(string $query, int $field = 0) {
+function get_val(string $query, int $field = 0): string {
 	global $connection;
 	return $connection->result($query, $field);
 }
@@ -199,7 +186,7 @@ function get_val(string $query, int $field = 0) {
 * @param mixed $column
 * @return list<string>
 */
-function get_vals(string $query, $column = 0) {
+function get_vals(string $query, $column = 0): array {
 	global $connection;
 	$return = array();
 	$result = $connection->query($query);
@@ -214,7 +201,7 @@ function get_vals(string $query, $column = 0) {
 /** Get keys from first column and values from second
 * @return string[]
 */
-function get_key_vals(string $query, Db $connection2 = null, bool $set_keys = true) {
+function get_key_vals(string $query, Db $connection2 = null, bool $set_keys = true): array {
 	global $connection;
 	if (!is_object($connection2)) {
 		$connection2 = $connection;
@@ -236,7 +223,7 @@ function get_key_vals(string $query, Db $connection2 = null, bool $set_keys = tr
 /** Get all rows of result
 * @return list<string[]> of associative arrays
 */
-function get_rows(string $query, Db $connection2 = null, string $error = "<p class='error'>") {
+function get_rows(string $query, Db $connection2 = null, string $error = "<p class='error'>"): array {
 	global $connection;
 	$conn = (is_object($connection2) ? $connection2 : $connection);
 	$return = array();
@@ -272,9 +259,8 @@ function unique_array(array $row, array $indexes) {
 }
 
 /** Escape column key used in where()
-* @return string
 */
-function escape_key(string $key) {
+function escape_key(string $key): string {
 	if (preg_match('(^([\w(]+)(' . str_replace("_", ".*", preg_quote(idf_escape("_"))) . ')([ \w)]+)$)', $key, $match)) { //! columns looking like functions
 		return $match[1] . idf_escape(idf_unescape($match[2])) . $match[3]; //! SQL injection
 	}
@@ -284,9 +270,8 @@ function escape_key(string $key) {
 /** Create SQL condition from parsed query string
 * @param array{where:string[], null:list<string>} $where parsed query string
 * @param Field[] $fields
-* @return string
 */
-function where(array $where, array $fields = array()) {
+function where(array $where, array $fields = array()): string {
 	global $connection;
 	$return = array();
 	foreach ((array) $where["where"] as $key => $val) {
@@ -312,9 +297,8 @@ function where(array $where, array $fields = array()) {
 
 /** Create SQL condition from query string
 * @param Field[] $fields
-* @return string
 */
-function where_check(string $val, array $fields = array()) {
+function where_check(string $val, array $fields = array()): string {
 	parse_str($val, $check);
 	remove_slashes(array(&$check));
 	return where($check, $fields);
@@ -323,9 +307,8 @@ function where_check(string $val, array $fields = array()) {
 /** Create query string where condition from value
 * @param int $i condition order
 * @param string $column column identifier
-* @return string
 */
-function where_link(int $i, string $column, string $value, string $operator = "=") {
+function where_link(int $i, string $column, string $value, string $operator = "="): string {
 	return "&where%5B$i%5D%5Bcol%5D=" . urlencode($column) . "&where%5B$i%5D%5Bop%5D=" . urlencode(($value !== null ? $operator : "IS NULL")) . "&where%5B$i%5D%5Bval%5D=" . urlencode($value);
 }
 
@@ -333,9 +316,8 @@ function where_link(int $i, string $column, string $value, string $operator = "=
 * @param mixed[] $columns only keys are used
 * @param Field[] $fields
 * @param list<string> $select
-* @return string
 */
-function convert_fields(array $columns, array $fields, array $select = array()) {
+function convert_fields(array $columns, array $fields, array $select = array()): string {
 	$return = "";
 	foreach ($columns as $key => $val) {
 		if ($select && !in_array(idf_escape($key), $select)) {
@@ -351,9 +333,8 @@ function convert_fields(array $columns, array $fields, array $select = array())
 
 /** Set cookie valid on current path
 * @param int $lifetime number of seconds, 0 for session cookie, 2592000 - 30 days
-* @return void
 */
-function cookie(string $name, string $value, int $lifetime = 2592000) {
+function cookie(string $name, string $value, int $lifetime = 2592000): void {
 	global $HTTPS;
 	header(
 		"Set-Cookie: $name=" . urlencode($value)
@@ -368,7 +349,7 @@ function cookie(string $name, string $value, int $lifetime = 2592000) {
 /** Get settings stored in a cookie
 * @return mixed[]
 */
-function get_settings(string $cookie) {
+function get_settings(string $cookie): array {
 	parse_str($_COOKIE[$cookie], $settings);
 	return $settings;
 }
@@ -383,25 +364,22 @@ function get_setting(string $key, string $cookie = "adminer_settings") {
 
 /** Store settings to a cookie
 * @param mixed[] $settings
-* @return void
 */
-function save_settings(array $settings, string $cookie = "adminer_settings") {
+function save_settings(array $settings, string $cookie = "adminer_settings"): void {
 	cookie($cookie, http_build_query($settings + get_settings($cookie)));
 }
 
 /** Restart stopped session
-* @return void
 */
-function restart_session() {
+function restart_session(): void {
 	if (!ini_bool("session.use_cookies") && (!function_exists('session_status') || session_status() == 1)) { // 1 - PHP_SESSION_NONE, session_status() available since PHP 5.4
 		session_start();
 	}
 }
 
 /** Stop session if possible
-* @return void
 */
-function stop_session(bool $force = false) {
+function stop_session(bool $force = false): void {
 	$use_cookies = ini_bool("session.use_cookies");
 	if (!$use_cookies || $force) {
 		session_write_close(); // improves concurrency if a user opens several pages at once, may be restarted later
@@ -427,9 +405,8 @@ function set_session(string $key, $val) {
 }
 
 /** Get authenticated URL
-* @return string
 */
-function auth_url(string $vendor, string $server, string $username, string $db = null) {
+function auth_url(string $vendor, string $server, string $username, string $db = null): string {
 	global $drivers;
 	$uri = remove_from_uri(implode("|", array_keys($drivers))
 		. "|username|ext|"
@@ -449,17 +426,15 @@ function auth_url(string $vendor, string $server, string $username, string $db =
 }
 
 /** Find whether it is an AJAX request
-* @return bool
 */
-function is_ajax() {
+function is_ajax(): bool {
 	return ($_SERVER["HTTP_X_REQUESTED_WITH"] == "XMLHttpRequest");
 }
 
 /** Send Location header and exit
 * @param string $location null to only set a message
-* @return void
 */
-function redirect(string $location, string $message = null) {
+function redirect(string $location, string $message = null): void {
 	if ($message !== null) {
 		restart_session();
 		$_SESSION["messages"][preg_replace('~^[^?]*~', '', ($location !== null ? $location : $_SERVER["REQUEST_URI"]))][] = $message;
@@ -474,9 +449,8 @@ function redirect(string $location, string $message = null) {
 }
 
 /** Execute query and redirect if successful
-* @return bool
 */
-function query_redirect(string $query, string $location, string $message, bool $redirect = true, bool $execute = true, bool $failed = false, string $time = "") {
+function query_redirect(string $query, string $location, string $message, bool $redirect = true, bool $execute = true, bool $failed = false, string $time = ""): bool {
 	global $connection, $error, $adminer;
 	if ($execute) {
 		$start = microtime(true);
@@ -518,9 +492,8 @@ function queries(string $query) {
 /** Apply command to all array items
 * @param list<string> $tables
 * @param callable(string):string $escape
-* @return bool
 */
-function apply_queries(string $query, array $tables, callable $escape = 'Adminer\table') {
+function apply_queries(string $query, array $tables, callable $escape = 'Adminer\table'): bool {
 	foreach ($tables as $table) {
 		if (!queries("$query " . $escape($table))) {
 			return false;
@@ -530,9 +503,8 @@ function apply_queries(string $query, array $tables, callable $escape = 'Adminer
 }
 
 /** Redirect by remembered queries
-* @return bool
 */
-function queries_redirect(string $location, string $message, bool $redirect) {
+function queries_redirect(string $location, string $message, bool $redirect): bool {
 	$queries = implode("\n", Queries::$queries);
 	$time = format_time(Queries::$start);
 	return query_redirect($queries, $location, $message, $redirect, false, !$redirect, $time);
@@ -542,21 +514,19 @@ function queries_redirect(string $location, string $message, bool $redirect) {
 * @param float $start output of microtime(true)
 * @return string HTML code
 */
-function format_time(float $start) {
+function format_time(float $start): string {
 	return lang('%.3f s', max(0, microtime(true) - $start));
 }
 
 /** Get relative REQUEST_URI
-* @return string
 */
-function relative_uri() {
+function relative_uri(): string {
 	return str_replace(":", "%3a", preg_replace('~^[^?]*/([^?]*)~', '\1', $_SERVER["REQUEST_URI"]));
 }
 
 /** Remove parameter from query string
-* @return string
 */
-function remove_from_uri(string $param = "") {
+function remove_from_uri(string $param = ""): string {
 	return substr(preg_replace("~(?<=[?&])($param" . (SID ? "" : "|" . session_name()) . ")=[^&]*&~", '', relative_uri() . "&"), 0, -1);
 }
 
@@ -600,25 +570,22 @@ function get_file(string $key, bool $decompress = false, string $delimiter = "")
 }
 
 /** Determine upload error
-* @return string
 */
-function upload_error(int $error) {
+function upload_error(int $error): string {
 	$max_size = ($error == UPLOAD_ERR_INI_SIZE ? ini_get("upload_max_filesize") : 0); // post_max_size is checked in index.php
 	return ($error ? lang('Unable to upload a file.') . ($max_size ? " " . lang('Maximum allowed file size is %sB.', $max_size) : "") : lang('File does not exist.'));
 }
 
 /** Create repeat pattern for preg
-* @return string
 */
-function repeat_pattern(string $pattern, int $length) {
+function repeat_pattern(string $pattern, int $length): string {
 	// fix for Compilation failed: number too big in {} quantifier
 	return str_repeat("$pattern{0,65535}", $length / 65535) . "$pattern{0," . ($length % 65535) . "}"; // can create {0,0} which is OK
 }
 
 /** Check whether the string is in UTF-8
-* @return bool
 */
-function is_utf8(string $val) {
+function is_utf8(string $val): bool {
 	// don't print control chars except \t\r\n
 	return (preg_match('~~u', $val) && !preg_match('~[\0-\x8\xB\xC\xE-\x1F]~', $val));
 }
@@ -626,7 +593,7 @@ function is_utf8(string $val) {
 /** Shorten UTF-8 string
 * @return string escaped string with appended ...
 */
-function shorten_utf8(string $string, int $length = 80, string $suffix = "") {
+function shorten_utf8(string $string, int $length = 80, string $suffix = ""): string {
 	if (!preg_match("(^(" . repeat_pattern("[\t\r\n -\x{10FFFF}]", $length) . ")($)?)u", $string, $match)) { // ~s causes trash in $match[2] under some PHP versions, (.|\n) is slow
 		preg_match("(^(" . repeat_pattern("[\t\r\n -~]", $length) . ")($)?)", $string, $match);
 	}
@@ -635,16 +602,14 @@ function shorten_utf8(string $string, int $length = 80, string $suffix = "") {
 
 /** Format decimal number
 * @param float|numeric-string $val
-* @return string
 */
-function format_number($val) {
+function format_number($val): string {
 	return strtr(number_format($val, 0, ".", lang(',')), preg_split('~~u', lang('0123456789'), -1, PREG_SPLIT_NO_EMPTY));
 }
 
 /** Generate friendly URL
-* @return string
 */
-function friendly_url(string $val) {
+function friendly_url(string $val): string {
 	// used for blobs and export
 	return preg_replace('~\W~i', '-', $val);
 }
@@ -652,7 +617,7 @@ function friendly_url(string $val) {
 /** Get status of a single table and fall back to name on error
 * @return TableStatus one element from table_status()
 */
-function table_status1(string $table, bool $fast = false) {
+function table_status1(string $table, bool $fast = false): array {
 	$return = table_status($table, $fast);
 	return ($return ? reset($return) : array("Name" => $table));
 }
@@ -660,7 +625,7 @@ function table_status1(string $table, bool $fast = false) {
 /** Find out foreign keys for each column
 * @return list<ForeignKey>[] [$col => []]
 */
-function column_foreign_keys(string $table) {
+function column_foreign_keys(string $table): array {
 	global $adminer;
 	$return = array();
 	foreach ($adminer->foreignKeys($table) as $foreign_key) {
@@ -674,7 +639,7 @@ function column_foreign_keys(string $table) {
 /** Compute fields() from $_POST edit data
 * @return Field[] same as fields()
 */
-function fields_from_edit() { // used by Mongo and SimpleDB
+function fields_from_edit(): array { // used by Mongo and SimpleDB
 	global $driver;
 	$return = array();
 	foreach ((array) $_POST["field_keys"] as $key => $val) {
@@ -699,7 +664,7 @@ function fields_from_edit() { // used by Mongo and SimpleDB
 /** Send headers for export
 * @return string extension
 */
-function dump_headers(string $identifier, bool $multi_table = false) {
+function dump_headers(string $identifier, bool $multi_table = false): string {
 	global $adminer;
 	$return = $adminer->dumpHeaders($identifier, $multi_table);
 	$output = $_POST["output"];
@@ -717,9 +682,8 @@ function dump_headers(string $identifier, bool $multi_table = false) {
 
 /** Print CSV row
 * @param string[] $row
-* @return void
 */
-function dump_csv(array $row) {
+function dump_csv(array $row): void {
 	foreach ($row as $key => $val) {
 		if (preg_match('~["\n,;\t]|^0|\.\d*0$~', $val) || $val === "") {
 			$row[$key] = '"' . str_replace('"', '""', $val) . '"';
@@ -730,16 +694,14 @@ function dump_csv(array $row) {
 
 /** Apply SQL function
 * @param string $column escaped column identifier
-* @return string
 */
-function apply_sql_function(string $function, string $column) {
+function apply_sql_function(string $function, string $column): string {
 	return ($function ? ($function == "unixepoch" ? "DATETIME($column, '$function')" : ($function == "count distinct" ? "COUNT(DISTINCT " : strtoupper("$function(")) . "$column)") : $column);
 }
 
 /** Get path of the temporary directory
-* @return string
 */
-function get_temp_dir() {
+function get_temp_dir(): string {
 	$return = ini_get("upload_tmp_dir"); // session_save_path() may contain other storage path
 	if (!$return) {
 		if (function_exists('sys_get_temp_dir')) {
@@ -776,9 +738,8 @@ function file_open_lock(string $filename) {
 }
 
 /** Write and unlock a file
-* @return void
 */
-function file_write_unlock(resource $fp, string $data) {
+function file_write_unlock(resource $fp, string $data): void {
 	rewind($fp);
 	fwrite($fp, $data);
 	ftruncate($fp, strlen($data));
@@ -786,9 +747,8 @@ function file_write_unlock(resource $fp, string $data) {
 }
 
 /** Unlock and close a file
-* @return void
 */
-function file_unlock(resource $fp) {
+function file_unlock(resource $fp): void {
 	flock($fp, LOCK_UN);
 	fclose($fp);
 }
@@ -827,7 +787,7 @@ function password_file(bool $create) {
 /** Get a random string
 * @return string 32 hexadecimal characters
 */
-function rand_string() {
+function rand_string(): string {
 	return md5(uniqid(strval(mt_rand()), true));
 }
 
@@ -836,7 +796,7 @@ function rand_string() {
 * @param Field $field
 * @return string HTML
 */
-function select_value($val, string $link, array $field, int $text_length) {
+function select_value($val, string $link, array $field, int $text_length): string {
 	global $adminer;
 	if (is_array($val)) {
 		$return = "";
@@ -873,9 +833,8 @@ function select_value($val, string $link, array $field, int $text_length) {
 }
 
 /** Check whether the string is e-mail address
-* @return bool
 */
-function is_mail(?string $email) {
+function is_mail(?string $email): bool {
 	$atom = '[-a-z0-9!#$%&\'*+/=?^_`{|}~]'; // characters of local-name
 	$domain = '[a-z0-9]([-a-z0-9]{0,61}[a-z0-9])'; // one domain component
 	$pattern = "$atom+(\\.$atom+)*@($domain?\\.)+$domain";
@@ -883,27 +842,24 @@ function is_mail(?string $email) {
 }
 
 /** Check whether the string is URL address
-* @return bool
 */
-function is_url(string $string) {
+function is_url(string $string): bool {
 	$domain = '[a-z0-9]([-a-z0-9]{0,61}[a-z0-9])'; // one domain component //! IDN
 	return preg_match("~^(https?)://($domain?\\.)+$domain(:\\d+)?(/.*)?(\\?.*)?(#.*)?\$~i", $string); //! restrict path, query and fragment characters
 }
 
 /** Check if field should be shortened
 * @param Field $field
-* @return bool
 */
-function is_shortable(array $field) {
+function is_shortable(array $field): bool {
 	return preg_match('~char|text|json|lob|geometry|point|linestring|polygon|string|bytea~', $field["type"]);
 }
 
 /** Get query to compute number of found rows
 * @param list<string> $where
 * @param list<string> $group
-* @return string
 */
-function count_rows(string $table, array $where, bool $is_group, array $group) {
+function count_rows(string $table, array $where, bool $is_group, array $group): string {
 	$query = " FROM " . table($table) . ($where ? " WHERE " . implode(" AND ", $where) : "");
 	return ($is_group && (JUSH == "sql" || count($group) == 1)
 		? "SELECT COUNT(DISTINCT " . implode(", ", $group) . ")$query"
@@ -914,7 +870,7 @@ function count_rows(string $table, array $where, bool $is_group, array $group) {
 /** Run query which can be killed by AJAX call after timing out
 * @return string[]
 */
-function slow_query(string $query) {
+function slow_query(string $query): array {
 	global $adminer, $token, $driver;
 	$db = $adminer->database();
 	$timeout = $adminer->queryTimeout();
@@ -939,26 +895,23 @@ function slow_query(string $query) {
 }
 
 /** Generate BREACH resistant CSRF token
-* @return string
 */
-function get_token() {
+function get_token(): string {
 	$rand = rand(1, 1e6);
 	return ($rand ^ $_SESSION["token"]) . ":$rand";
 }
 
 /** Verify if supplied CSRF token is valid
-* @return bool
 */
-function verify_token() {
+function verify_token(): bool {
 	list($token, $rand) = explode(":", $_POST["token"]);
 	return ($rand ^ $_SESSION["token"]) == $token;
 }
 
 // used in compiled version
 /**
-* @return string
 */
-function lzw_decompress(string $binary) {
+function lzw_decompress(string $binary): string {
 	// convert binary string to codes
 	$dictionary_count = 256;
 	$bits = 8; // ceil(log($dictionary_count, 2))
diff --git a/adminer/include/html.inc.php b/adminer/include/html.inc.php
index af7995a4..9b7cb642 100644
--- a/adminer/include/html.inc.php
+++ b/adminer/include/html.inc.php
@@ -2,23 +2,20 @@
 namespace Adminer;
 
 /** Return <script> element
-* @return string
 */
-function script(string $source, string $trailing = "\n") {
+function script(string $source, string $trailing = "\n"): string {
 	return "<script" . nonce() . ">$source</script>$trailing";
 }
 
 /** Return <script src> element
-* @return string
 */
-function script_src(string $url) {
+function script_src(string $url): string {
 	return "<script src='" . h($url) . "'" . nonce() . "></script>\n";
 }
 
 /** Get a nonce="" attribute with CSP nonce
-* @return string
 */
-function nonce() {
+function nonce(): string {
 	return ' nonce="' . get_nonce() . '"';
 }
 
@@ -26,7 +23,7 @@ function nonce() {
 * @param string|int $value
 * @return string HTML
 */
-function input_hidden(string $name, $value = "") {
+function input_hidden(string $name, $value = ""): string {
 	return "<input type='hidden' name='" . h($name) . "' value='" . h($value) . "'>\n";
 }
 
@@ -34,37 +31,33 @@ function input_hidden(string $name, $value = "") {
 * @param string $special token to use instead of global $token
 * @return string HTML
 */
-function input_token(string $special = "") {
+function input_token(string $special = ""): string {
 	global $token;
 	return input_hidden("token", ($special ?: $token));
 }
 
 /** Get a target="_blank" attribute
-* @return string
 */
-function target_blank() {
+function target_blank(): string {
 	return ' target="_blank" rel="noreferrer noopener"';
 }
 
 /** Escape for HTML
-* @return string
 */
-function h(string $string) {
+function h(string $string): string {
 	return str_replace("\0", "&#0;", htmlspecialchars($string, ENT_QUOTES, 'utf-8'));
 }
 
 /** Convert \n to <br>
-* @return string
 */
-function nl_br(string $string) {
+function nl_br(string $string): string {
 	return str_replace("\n", "<br>", $string); // nl2br() uses XHTML before PHP 5.3
 }
 
 /** Generate HTML checkbox
 * @param string|int $value
-* @return string
 */
-function checkbox(string $name, $value, bool $checked, string $label = "", string $onclick = "", string $class = "", string $labelled_by = "") {
+function checkbox(string $name, $value, bool $checked, string $label = "", string $onclick = "", string $class = "", string $labelled_by = ""): string {
 	$return = "<input type='checkbox' name='$name' value='" . h($value) . "'"
 		. ($checked ? " checked" : "")
 		. ($labelled_by ? " aria-labelledby='$labelled_by'" : "")
@@ -78,9 +71,8 @@ function checkbox(string $name, $value, bool $checked, string $label = "", strin
 * @param string[]|string[][] $options array of strings or arrays (creates optgroup)
 * @param mixed $selected
 * @param bool $use_keys always use array keys for value="", otherwise only string keys are used
-* @return string
 */
-function optionlist($options, $selected = null, bool $use_keys = false) {
+function optionlist($options, $selected = null, bool $use_keys = false): string {
 	$return = "";
 	foreach ($options as $k => $v) {
 		$opts = array($k => $v);
@@ -104,9 +96,8 @@ function optionlist($options, $selected = null, bool $use_keys = false) {
 
 /** Generate HTML <select>
 * @param string[] $options
-* @return string
 */
-function html_select(string $name, array $options, string $value = "", string $onchange = "", string $labelled_by = "") {
+function html_select(string $name, array $options, string $value = "", string $onchange = "", string $labelled_by = ""): string {
 	return "<select name='" . h($name) . "'"
 		. ($labelled_by ? " aria-labelledby='$labelled_by'" : "")
 		. ">" . optionlist($options, $value) . "</select>"
@@ -116,9 +107,8 @@ function html_select(string $name, array $options, string $value = "", string $o
 
 /** Generate HTML radio list
 * @param string[] $options
-* @return string
 */
-function html_radios(string $name, array $options, string $value = "") {
+function html_radios(string $name, array $options, string $value = ""): string {
 	$return = "";
 	foreach ($options as $key => $val) {
 		$return .= "<label><input type='radio' name='" . h($name) . "' value='" . h($key) . "'" . ($key == $value ? " checked" : "") . ">" . h($val) . "</label>";
@@ -127,16 +117,14 @@ function html_radios(string $name, array $options, string $value = "") {
 }
 
 /** Get onclick confirmation
-* @return string
 */
-function confirm(string $message = "", string $selector = "qsl('input')") {
+function confirm(string $message = "", string $selector = "qsl('input')"): string {
 	return script("$selector.onclick = () => confirm('" . ($message ? js_escape($message) : lang('Are you sure?')) . "');", "");
 }
 
 /** Print header for hidden fieldset (close by </div></fieldset>)
-* @return void
 */
-function print_fieldset(string $id, string $legend, bool $visible = false) {
+function print_fieldset(string $id, string $legend, bool $visible = false): void {
 	echo "<fieldset><legend>";
 	echo "<a href='#fieldset-$id'>$legend</a>";
 	echo script("qsl('a').onclick = partial(toggle, 'fieldset-$id');", "");
@@ -145,23 +133,20 @@ function print_fieldset(string $id, string $legend, bool $visible = false) {
 }
 
 /** Return class='active' if $bold is true
-* @return string
 */
-function bold(bool $bold, string $class = "") {
+function bold(bool $bold, string $class = ""): string {
 	return ($bold ? " class='active $class'" : ($class ? " class='$class'" : ""));
 }
 
 /** Escape string for JavaScript apostrophes
-* @return string
 */
-function js_escape(string $string) {
+function js_escape(string $string): string {
 	return addcslashes($string, "\r\n'\\/"); // slash for <script>
 }
 
 /** Generate page number for pagination
-* @return string
 */
-function pagination(int $page, int $current) {
+function pagination(int $page, int $current): string {
 	return " " . ($page == $current
 		? $page + 1
 		: '<a href="' . h(remove_from_uri("page") . ($page ? "&page=$page" . ($_GET["next"] ? "&next=" . urlencode($_GET["next"]) : "") : "")) . '">' . ($page + 1) . "</a>"
@@ -171,9 +156,8 @@ function pagination(int $page, int $current) {
 /** Print hidden fields
 * @param mixed[] $process
 * @param list<string> $ignore
-* @return bool
 */
-function hidden_fields(array $process, array $ignore = array(), string $prefix = '') {
+function hidden_fields(array $process, array $ignore = array(), string $prefix = ''): bool {
 	$return = false;
 	foreach ($process as $key => $val) {
 		if (!in_array($key, $ignore)) {
@@ -189,9 +173,8 @@ function hidden_fields(array $process, array $ignore = array(), string $prefix =
 }
 
 /** Print hidden fields for GET forms
-* @return void
 */
-function hidden_fields_get() {
+function hidden_fields_get(): void {
 	echo (sid() ? input_hidden(session_name(), session_id()) : '');
 	echo (SERVER !== null ? input_hidden(DRIVER, SERVER) : "");
 	echo input_hidden("username", $_GET["username"]);
@@ -201,9 +184,8 @@ function hidden_fields_get() {
 * @param string $type "radio"|"checkbox"
 * @param Field $field
 * @param mixed $value string|array
-* @return string
 */
-function enum_input(string $type, string $attrs, array $field, $value, string $empty = null) {
+function enum_input(string $type, string $attrs, array $field, $value, string $empty = null): string {
 	global $adminer;
 	preg_match_all("~'((?:[^']|'')*)'~", $field["length"], $matches);
 	$return = ($empty !== null ? "<label><input type='$type'$attrs value='$empty'" . ((is_array($value) ? in_array($empty, $value) : $value === $empty) ? " checked" : "") . "><i>" . lang('empty') . "</i></label>" : "");
@@ -218,9 +200,8 @@ function enum_input(string $type, string $attrs, array $field, $value, string $e
 /** Print edit input field
 * @param Field|RoutineField $field one field from fields()
 * @param mixed $value
-* @return void
 */
-function input(array $field, $value, string $function, bool $autofocus = false) {
+function input(array $field, $value, string $function, bool $autofocus = false): void {
 	global $driver, $adminer;
 	$name = h(bracket_escape($field["field"]));
 	echo "<td class='function'>";
@@ -362,9 +343,8 @@ function process_input(array $field) {
 /** Print results of search in all tables
 * @uses $_GET["where"][0]
 * @uses $_POST["tables"]
-* @return void
 */
-function search_tables() {
+function search_tables(): void {
 	global $adminer, $connection;
 	$_GET["where"][0]["val"] = $_POST["query"];
 	$sep = "<ul>\n";
@@ -385,18 +365,16 @@ function search_tables() {
 /** Return events to display help on mouse over
 * @param string $command JS expression
 * @param int $side JS expression
-* @return string
 */
-function on_help(string $command, int $side = 0) {
+function on_help(string $command, int $side = 0): string {
 	return script("mixin(qsl('select, input'), {onmouseover: function (event) { helpMouseover.call(this, event, $command, $side) }, onmouseout: helpMouseout});", "");
 }
 
 /** Print edit data form
 * @param Field[] $fields
 * @param mixed $row
-* @return void
 */
-function edit_form(string $table, array $fields, $row, bool $update) {
+function edit_form(string $table, array $fields, $row, bool $update): void {
 	global $adminer, $error;
 	$table_name = $adminer->tableName(table_status1($table, true));
 	page_header(
@@ -501,8 +479,7 @@ function edit_form(string $table, array $fields, $row, bool $update) {
 }
 
 /** Get button with icon
-* @return string
 */
-function icon(string $icon, string $name, string $html, string $title) {
+function icon(string $icon, string $name, string $html, string $title): string {
 	return "<button type='submit' name='$name' title='" . h($title) . "' class='icon icon-$icon'><span>$html</span></button>";
 }
diff --git a/adminer/include/lang.inc.php b/adminer/include/lang.inc.php
index bcce58c4..a57ee868 100644
--- a/adminer/include/lang.inc.php
+++ b/adminer/include/lang.inc.php
@@ -52,9 +52,8 @@ $langs = array(
 );
 
 /** Get current language
-* @return string
 */
-function get_lang() {
+function get_lang(): string {
 	global $LANG;
 	return $LANG;
 }
@@ -62,9 +61,8 @@ function get_lang() {
 /** Translate string
 * @param literal-string $idf
 * @param float|string $number
-* @return string
 */
-function lang(string $idf, $number = null) {
+function lang(string $idf, $number = null): string {
 	// this is matched by compile.php
 	global $LANG, $translations;
 	$translation = ($translations[$idf] ?: $idf);
@@ -92,8 +90,7 @@ function lang(string $idf, $number = null) {
 	return vsprintf($format, $args);
 }
 
-/** @return void */
-function switch_lang() {
+function switch_lang(): void {
 	global $LANG, $langs;
 	echo "<form action='' method='post'>\n<div id='lang'>";
 	echo lang('Language') . ": " . html_select("lang", $langs, $LANG, "this.form.submit();");
diff --git a/adminer/include/pdo.inc.php b/adminer/include/pdo.inc.php
index ba8a6a2b..f37aa31a 100644
--- a/adminer/include/pdo.inc.php
+++ b/adminer/include/pdo.inc.php
@@ -8,9 +8,8 @@ if (extension_loaded('pdo')) {
 
 		/** Connect to server using DSN
 		* @param mixed[] $options
-		* @return void
 		*/
-		function dsn(string $dsn, string $username, string $password, array $options = array()) {
+		function dsn(string $dsn, string $username, string $password, array $options = array()): void {
 			$options[\PDO::ATTR_ERRMODE] = \PDO::ERRMODE_SILENT;
 			$options[\PDO::ATTR_STATEMENT_CLASS] = array('Adminer\PdoResult');
 			try {
diff --git a/adminer/include/tmpfile.inc.php b/adminer/include/tmpfile.inc.php
index 5b26864a..9f432e11 100644
--- a/adminer/include/tmpfile.inc.php
+++ b/adminer/include/tmpfile.inc.php
@@ -10,15 +10,13 @@ class TmpFile {
 	}
 
 	/**
-	* @return void
 	*/
-	function write(string $contents) {
+	function write(string $contents): void {
 		$this->size += strlen($contents);
 		fwrite($this->handler, $contents);
 	}
 
-	/** @return void */
-	function send() {
+	function send(): void {
 		fseek($this->handler, 0);
 		fpassthru($this->handler);
 		fclose($this->handler);
diff --git a/adminer/include/xxtea.inc.php b/adminer/include/xxtea.inc.php
index 197fab73..562adad1 100644
--- a/adminer/include/xxtea.inc.php
+++ b/adminer/include/xxtea.inc.php
@@ -7,9 +7,8 @@ namespace Adminer;
 */
 
 /**
-* @return int
 */
-function int32(int $n) {
+function int32(int $n): int {
 	while ($n >= 2147483648) {
 		$n -= 4294967296;
 	}
@@ -21,9 +20,8 @@ function int32(int $n) {
 
 /**
 * @param int[] $v
-* @return string
 */
-function long2str(array $v, bool $w) {
+function long2str(array $v, bool $w): string {
 	$s = '';
 	foreach ($v as $val) {
 		$s .= pack('V', $val);
@@ -37,7 +35,7 @@ function long2str(array $v, bool $w) {
 /**
 * @return int[]
 */
-function str2long(string $s, bool $w) {
+function str2long(string $s, bool $w): array {
 	$v = array_values(unpack('V*', str_pad($s, 4 * ceil(strlen($s) / 4), "\0")));
 	if ($w) {
 		$v[] = strlen($s);
@@ -46,9 +44,8 @@ function str2long(string $s, bool $w) {
 }
 
 /**
-* @return int
 */
-function xxtea_mx(int $z, int $y, int $sum, int $k) {
+function xxtea_mx(int $z, int $y, int $sum, int $k): int {
 	return int32((($z >> 5 & 0x7FFFFFF) ^ $y << 2) + (($y >> 3 & 0x1FFFFFFF) ^ $z << 4)) ^ int32(($sum ^ $y) + ($k ^ $z));
 }
 
@@ -56,7 +53,7 @@ function xxtea_mx(int $z, int $y, int $sum, int $k) {
 * @param string $str plain-text password
 * @return string binary cipher
 */
-function encrypt_string(string $str, string $key) {
+function encrypt_string(string $str, string $key): string {
 	if ($str == "") {
 		return "";
 	}
diff --git a/compile.php b/compile.php
index 04aff5cf..ac69bcbf 100755
--- a/compile.php
+++ b/compile.php
@@ -87,7 +87,7 @@ function put_file($match) {
 	}
 	if (basename($match[2]) != "lang.inc.php" || !$_SESSION["lang"]) {
 		if (basename($match[2]) == "lang.inc.php") {
-			$return = str_replace('function lang(string $idf, $number = null) {', 'function lang($idf, $number = null) {
+			$return = str_replace('function lang(string $idf, $number = null): string {', 'function lang($idf, $number = null) {
 	if (is_string($idf)) { // compiled version uses numbers, string comes from a plugin
 		// English translation is closest to the original identifiers //! pluralized translations are not found
 		$pos = array_search($idf, get_translations("en")); //! this should be cached
diff --git a/editor/include/editing.inc.php b/editor/include/editing.inc.php
index 59b8c7cc..5c4b49de 100644
--- a/editor/include/editing.inc.php
+++ b/editor/include/editing.inc.php
@@ -2,18 +2,16 @@
 namespace Adminer;
 
 /** Encode e-mail header in UTF-8
-* @return string
 */
-function email_header(string $header) {
+function email_header(string $header): string {
 	// iconv_mime_encode requires iconv, imap_8bit requires IMAP extension
 	return "=?UTF-8?B?" . base64_encode($header) . "?="; //! split long lines
 }
 
 /** Send e-mail in UTF-8
 * @param array{error?:list<int>, type?:list<string>, name?:list<string>, tmp_name?:list<string>} $files
-* @return bool
 */
-function send_mail(string $email, string $subject, string $message, string $from = "", array $files = array()) {
+function send_mail(string $email, string $subject, string $message, string $from = "", array $files = array()): bool {
 	$eol = PHP_EOL;
 	$message = str_replace("\n", $eol, wordwrap(str_replace("\r", "", "$message\n")));
 	$boundary = uniqid("boundary");
@@ -43,8 +41,7 @@ function send_mail(string $email, string $subject, string $message, string $from
 
 /** Check whether the column looks like boolean
 * @param Field $field single field returned from fields()
-* @return bool
 */
-function like_bool(array $field) {
+function like_bool(array $field): bool {
 	return preg_match("~bool|(tinyint|bit)\\(1\\)~", $field["full_type"]);
 }
diff --git a/plugins/drivers/elastic.php b/plugins/drivers/elastic.php
index 47ec030c..31d8c680 100644
--- a/plugins/drivers/elastic.php
+++ b/plugins/drivers/elastic.php
@@ -66,9 +66,8 @@ if (isset($_GET["elastic"])) {
 			}
 
 			/**
-			 * @return bool
 			 */
-			function connect(string $server, string $username, string $password) {
+			function connect(string $server, string $username, string $password): bool {
 				preg_match('~^(https?://)?(.*)~', $server, $match);
 				$this->url = ($match[1] ?: "http://") . urlencode($username) . ":" . urlencode($password) . "@$match[2]";
 				$return = $this->query('');
@@ -543,9 +542,8 @@ if (isset($_GET["elastic"])) {
 
 	/** Drop types
 	 * @param list<string> $tables
-	 * @return bool
 	 */
-	function drop_tables(array $tables) {
+	function drop_tables(array $tables): bool {
 		$return = true;
 		foreach ($tables as $table) { //! convert to bulk api
 			$return = $return && connection()->query(urlencode($table), null, 'DELETE');
diff --git a/plugins/table-indexes-structure.php b/plugins/table-indexes-structure.php
index d59cb44a..5234bc02 100644
--- a/plugins/table-indexes-structure.php
+++ b/plugins/table-indexes-structure.php
@@ -10,9 +10,8 @@ class AdminerTableIndexesStructure {
 
 	/** Print table structure in tabular format
 	* @param Index[] $indexes data about all indexes on a table
-	* @return bool
 	*/
-	function tableIndexesPrint(array $indexes) {
+	function tableIndexesPrint(array $indexes): bool {
 		echo "<table>\n";
 		echo "<thead><tr><th>" . Adminer\lang('Name') . "<th>" . Adminer\lang('Type') . "<th>" . Adminer\lang('Columns') . "</thead>\n";
 		foreach ($indexes as $name => $index) {
diff --git a/plugins/table-structure.php b/plugins/table-structure.php
index f9c479e4..dbf11c15 100644
--- a/plugins/table-structure.php
+++ b/plugins/table-structure.php
@@ -10,9 +10,8 @@ class AdminerTableStructure {
 
 	/** Print table structure in tabular format
 	* @param Field[] $fields data about individual fields
-	* @return bool
 	*/
-	function tableStructurePrint(array $fields, $tableStatus = null) {
+	function tableStructurePrint(array $fields, $tableStatus = null): bool {
 		echo "<div class='scrollable'>\n";
 		echo "<table class='nowrap odds'>\n";
 		echo "<thead><tr>"