diff --git a/files/renderer.php b/files/renderer.php
index 14c8b358752..0795e9574c9 100644
--- a/files/renderer.php
+++ b/files/renderer.php
@@ -568,6 +568,9 @@ class files_tree_viewer implements renderable {
     public $path;
     public $context;
 
+    /** @var array file tree viewer options. */
+    protected array $options = [];
+
     /**
      * Constructor of moodle_file_tree_viewer class
      * @param file_info $file_info
diff --git a/mod/bigbluebuttonbn/classes/form/text_with_copy_element.php b/mod/bigbluebuttonbn/classes/form/text_with_copy_element.php
index 3d08933cd78..91c044c3283 100644
--- a/mod/bigbluebuttonbn/classes/form/text_with_copy_element.php
+++ b/mod/bigbluebuttonbn/classes/form/text_with_copy_element.php
@@ -32,6 +32,10 @@ require_once("$CFG->libdir/form/text.php");
  * @author     Laurent David  (laurent [at] call-learning [dt] fr)
  */
 class text_with_copy_element extends MoodleQuickForm_text {
+
+    /** @var string an element template. */
+    public $_groupElementTemplate;
+
     /**
      * Accepts a renderer
      *
diff --git a/mod/bigbluebuttonbn/classes/output/instance_updated_message.php b/mod/bigbluebuttonbn/classes/output/instance_updated_message.php
index b58ccea28cc..4ae73643ccc 100644
--- a/mod/bigbluebuttonbn/classes/output/instance_updated_message.php
+++ b/mod/bigbluebuttonbn/classes/output/instance_updated_message.php
@@ -45,6 +45,9 @@ class instance_updated_message implements renderable, templatable {
      */
     protected $instance;
 
+    /** @var int activity type. */
+    protected $type;
+
     /**
      * Instance updated constructor
      *
diff --git a/mod/bigbluebuttonbn/classes/recording.php b/mod/bigbluebuttonbn/classes/recording.php
index e7f3a262f86..fd8b7fb729d 100644
--- a/mod/bigbluebuttonbn/classes/recording.php
+++ b/mod/bigbluebuttonbn/classes/recording.php
@@ -81,6 +81,9 @@ class recording extends persistent {
     /** @var instance A cached copy of the instance */
     protected $instance;
 
+    /** @var bool imported recording status */
+    public $imported;
+
     /**
      * Create an instance of this class.
      *
diff --git a/mod/chat/chatd.php b/mod/chat/chatd.php
index 47a4297d90a..d576456245c 100644
--- a/mod/chat/chatd.php
+++ b/mod/chat/chatd.php
@@ -97,6 +97,45 @@ class ChatDaemon {
     public $setsinfo = array(); // Keyed by sessionid exactly like conn_sets, one of these for each of those.
     public $chatrooms = array(); // Keyed by chatid, holding arrays of data.
 
+    /** @var int error reporting level. */
+    public $_trace_level;
+
+    /** @var bool true if function_name exists and is a function, false otherwise. */
+    public $_pcntl_exists;
+
+    /** @var int */
+    public $_time_rest_socket;
+
+    /** @var string beep file location. */
+    public $_beepsoundsrc;
+
+    /** @var int update frequency records. */
+    public $_freq_update_records;
+
+    /** @var int upper limit value in seconds to detect a user has disconnected or not. */
+    public $_freq_poll_idle_chat;
+
+    /** @var resource|false a file pointer resource on success, or false on error. */
+    public $_stdout;
+
+    /** @var array user data with session ID as the key. */
+    public $sets_info = [];
+
+    /** @var array connection data with session ID as the key. */
+    public $conn_sets = [];
+
+    /** @var array connection data. */
+    public $conn_side = [];
+
+    /** @var array connection data. */
+    public $conn_half = [];
+
+    /** @var array connection data. */
+    public $conn_ufo = [];
+
+    /** @var resource|Socket socket resource. */
+    public $listen_socket;
+
     // IMPORTANT: $connectionssets, $setsinfo and $chatrooms must remain synchronized!
     //            Pay extra attention when you write code that affects any of them!
 
diff --git a/mod/chat/locallib.php b/mod/chat/locallib.php
index 06635fb8f3b..a21627f957d 100644
--- a/mod/chat/locallib.php
+++ b/mod/chat/locallib.php
@@ -35,6 +35,11 @@ class chat_portfolio_caller extends portfolio_module_caller_base {
     protected $start;
     /** @var int Timestamp */
     protected $end;
+    /** @var array Chat messages */
+    protected $messages = [];
+    /** @var bool True if participated, otherwise false. */
+    protected $participated;
+
     /**
      * @return array
      */
diff --git a/mod/feedback/classes/responses_table.php b/mod/feedback/classes/responses_table.php
index 58a9c241127..9b02e760139 100644
--- a/mod/feedback/classes/responses_table.php
+++ b/mod/feedback/classes/responses_table.php
@@ -78,6 +78,9 @@ class mod_feedback_responses_table extends table_sql {
     /** @var array the data structure containing the table data for the external function */
     protected $dataforexternal = [];
 
+    /** @var bool true if elements per page > 0, otherwise false. */
+    protected $pageable;
+
     /**
      * Constructor
      *
diff --git a/mod/feedback/item/feedback_item_form_class.php b/mod/feedback/item/feedback_item_form_class.php
index 7fb6379202e..10a25096860 100644
--- a/mod/feedback/item/feedback_item_form_class.php
+++ b/mod/feedback/item/feedback_item_form_class.php
@@ -19,6 +19,10 @@ require_once($CFG->libdir.'/formslib.php');
 define('FEEDBACK_ITEM_NAME_TEXTBOX_SIZE', 80);
 define('FEEDBACK_ITEM_LABEL_TEXTBOX_SIZE', 20);
 abstract class feedback_item_form extends moodleform {
+
+    /** @var string type value in the hidden element. */
+    protected $type;
+
     public function definition() {
         $item = $this->_customdata['item']; //the item object
 
diff --git a/mod/feedback/item/info/info_form.php b/mod/feedback/item/info/info_form.php
index 52b9c5dd7e9..82c8e73a8b8 100644
--- a/mod/feedback/item/info/info_form.php
+++ b/mod/feedback/item/info/info_form.php
@@ -19,6 +19,9 @@ require_once($CFG->dirroot.'/mod/feedback/item/feedback_item_form_class.php');
 class feedback_info_form extends feedback_item_form {
     protected $type = "info";
 
+    /** @var object Form element. */
+    protected $infotype;
+
     public function definition() {
 
         $item = $this->_customdata['item'];
diff --git a/mod/feedback/item/multichoicerated/multichoicerated_form.php b/mod/feedback/item/multichoicerated/multichoicerated_form.php
index 0dcd0f218d2..4d113b3662c 100644
--- a/mod/feedback/item/multichoicerated/multichoicerated_form.php
+++ b/mod/feedback/item/multichoicerated/multichoicerated_form.php
@@ -19,6 +19,9 @@ require_once($CFG->dirroot.'/mod/feedback/item/feedback_item_form_class.php');
 class feedback_multichoicerated_form extends feedback_item_form {
     protected $type = "multichoicerated";
 
+    /** @var object Form element */
+    protected $values;
+
     public function definition() {
         $item = $this->_customdata['item'];
         $common = $this->_customdata['common'];
diff --git a/mod/survey/tests/externallib_test.php b/mod/survey/tests/externallib_test.php
index 4cb49e83ffc..105bfd64ff8 100644
--- a/mod/survey/tests/externallib_test.php
+++ b/mod/survey/tests/externallib_test.php
@@ -38,6 +38,30 @@ require_once($CFG->dirroot . '/mod/survey/lib.php');
  */
 class externallib_test extends externallib_advanced_testcase {
 
+    /** @var \stdClass course record. */
+    protected $course;
+
+    /** @var \stdClass activity record. */
+    protected $survey;
+
+    /** @var \context_module context instance. */
+    protected $context;
+
+    /** @var \StdClass course module. */
+    protected $cm;
+
+    /** @var \StdClass student record. */
+    protected $student;
+
+    /** @var \StdClass teacher record. */
+    protected $teacher;
+
+    /** @var \StdClass student role. */
+    protected $studentrole;
+
+    /** @var \StdClass teacher role. */
+    protected $teacherrole;
+
     /**
      * Set up for every test
      */