diff --git a/admin/roles/tests/privacy/provider_test.php b/admin/roles/tests/privacy/provider_test.php
index fab062222a3..2504be7f822 100644
--- a/admin/roles/tests/privacy/provider_test.php
+++ b/admin/roles/tests/privacy/provider_test.php
@@ -187,7 +187,7 @@ class provider_test extends provider_testcase {
             $writer = writer::with_context($context);
             $this->assertTrue($writer->has_any_data());
             if ($context->contextlevel == CONTEXT_MODULE) {
-                if ($data = $writer->get_data($subcontextstudent)) {
+                if ($data = (array)$writer->get_data($subcontextstudent)) {
                     $this->assertEquals($user->id, reset($data)->userid);
                 }
                 if ($data = (array)$writer->get_data($subcontextrc)) {
diff --git a/admin/tool/behat/cli/run.php b/admin/tool/behat/cli/run.php
index a5dfa1d8b11..afaddd8b88d 100644
--- a/admin/tool/behat/cli/run.php
+++ b/admin/tool/behat/cli/run.php
@@ -278,7 +278,7 @@ if (empty($parallelrun)) {
     // Print combined run o/p from processes.
     $exitcodes = print_combined_run_output($processes, $stoponfail);
     // Time to finish run.
-    $time = round(microtime(true) - $time, 1);
+    $time = round(microtime(true) - $time, 0);
     echo "Finished in " . gmdate("G\h i\m s\s", $time) . PHP_EOL . PHP_EOL;
     ksort($exitcodes);
 
diff --git a/admin/tool/policy/classes/output/page_agreedocs.php b/admin/tool/policy/classes/output/page_agreedocs.php
index 8681715f945..d744f2729bb 100644
--- a/admin/tool/policy/classes/output/page_agreedocs.php
+++ b/admin/tool/policy/classes/output/page_agreedocs.php
@@ -278,7 +278,7 @@ class page_agreedocs implements renderable, templatable {
             $cache = \cache::make('core', 'presignup');
             $cachekey = 'tool_policy_viewedpolicies';
 
-            $viewedpolicies = $cache->get($cachekey);
+            $viewedpolicies = $cache->get($cachekey) ?: [];
             if (!empty($viewedpolicies)) {
                 // Get the list of the policies docs which the user haven't viewed during this session.
                 $pendingpolicies = array_diff($currentpolicyversionids, $viewedpolicies);
diff --git a/analytics/classes/calculation_info.php b/analytics/classes/calculation_info.php
index 2be73d21d5d..0d69d275f34 100644
--- a/analytics/classes/calculation_info.php
+++ b/analytics/classes/calculation_info.php
@@ -99,7 +99,7 @@ class calculation_info {
             $samplekey = self::get_sample_key($uniquesampleid);
 
             // Update the cached data adding the new indicator data.
-            $cacheddata = $cache->get($samplekey);
+            $cacheddata = $cache->get($samplekey) ?: [];
             $cacheddata[$calculableclass] = $infokeys;
             $cache->set($samplekey, $cacheddata);
         }
diff --git a/h5p/tests/helper_test.php b/h5p/tests/helper_test.php
index fedede87593..5e8622015d5 100644
--- a/h5p/tests/helper_test.php
+++ b/h5p/tests/helper_test.php
@@ -305,7 +305,9 @@ class helper_test extends \advanced_testcase {
         $this->assertTrue(empty($messages->info));
 
         // Add an some messages manually and check they are still there.
+        $messages->error = [];
         $messages->error['error1'] = 'Testing ERROR message';
+        $messages->info = [];
         $messages->info['info1'] = 'Testing INFO message';
         $messages->info['info2'] = 'Testing INFO message';
         helper::get_messages($messages, $factory);
diff --git a/lib/behat/classes/behat_config_util.php b/lib/behat/classes/behat_config_util.php
index cde958e2456..804d0a223ad 100644
--- a/lib/behat/classes/behat_config_util.php
+++ b/lib/behat/classes/behat_config_util.php
@@ -893,7 +893,7 @@ class behat_config_util {
                 && (!defined('PHPUNIT_TEST') || !PHPUNIT_TEST)) {
             echo "Bucket weightings:\n";
             foreach ($weights as $k => $weight) {
-                echo $k + 1 . ": " . str_repeat('*', 70 * $nbuckets * $weight / $totalweight) . PHP_EOL;
+                echo $k + 1 . ": " . str_repeat('*', (int)(70 * $nbuckets * $weight / $totalweight)) . PHP_EOL;
             }
         }
 
diff --git a/lib/classes/message/inbound/address_manager.php b/lib/classes/message/inbound/address_manager.php
index dbe7f26d94b..0d07227bb01 100644
--- a/lib/classes/message/inbound/address_manager.php
+++ b/lib/classes/message/inbound/address_manager.php
@@ -459,10 +459,8 @@ class address_manager {
      */
     protected function pack_int($int) {
         if (PHP_INT_SIZE === 8) {
-            $left = 0xffffffff00000000;
-            $right = 0x00000000ffffffff;
-            $l = ($int & $left) >>32;
-            $r = $int & $right;
+            $l = intdiv($int, pow(2, 32)); // 32-bit integer quotient.
+            $r = $int % pow(2, 32); // 32-bit integer remaining.
 
             return pack('NN', $l, $r);
         } else {
diff --git a/lib/classes/plugininfo/base.php b/lib/classes/plugininfo/base.php
index e7aed5c794b..40e20de4686 100644
--- a/lib/classes/plugininfo/base.php
+++ b/lib/classes/plugininfo/base.php
@@ -285,7 +285,8 @@ abstract class base {
         }
 
         if (isset($plugin->incompatible) && $plugin->incompatible !== null) {
-            if ((ctype_digit($plugin->incompatible) || is_int($plugin->incompatible)) && (int) $plugin->incompatible > 0) {
+            if (((is_string($plugin->incompatible) && ctype_digit($plugin->incompatible)) || is_int($plugin->incompatible))
+                    && (int) $plugin->incompatible > 0) {
                 $this->pluginincompatible = intval($plugin->incompatible);
             } else {
                 throw new coding_exception('Incorrect syntax in plugin incompatible declaration in '."$this->name");
diff --git a/lib/classes/session/redis.php b/lib/classes/session/redis.php
index c7e6d407772..157effda5e8 100644
--- a/lib/classes/session/redis.php
+++ b/lib/classes/session/redis.php
@@ -511,7 +511,7 @@ class redis extends handler {
                 // time. If it is too small we will poll too much and if it is
                 // too large we will waste time waiting for no reason. 100ms is
                 // the default starting point.
-                $delay = rand($this->lockretry, $this->lockretry * 1.1);
+                $delay = rand($this->lockretry, (int)($this->lockretry * 1.1));
             } else {
                 // If we don't get a lock within 5 seconds then there must be a
                 // very long lived process holding the lock so throttle back to
diff --git a/lib/completionlib.php b/lib/completionlib.php
index 46bad39d87a..aae0552e349 100644
--- a/lib/completionlib.php
+++ b/lib/completionlib.php
@@ -1055,7 +1055,7 @@ class completion_info {
             if (!isset($this->course->cacherev)) {
                 $this->course = get_course($this->course_id);
             }
-            if ($cacheddata = $completioncache->get($key)) {
+            if ($cacheddata = ($completioncache->get($key) ?: [])) {
                 if ($cacheddata['cacherev'] != $this->course->cacherev) {
                     // Course structure has been changed since the last caching, forget the cache.
                     $cacheddata = array();
diff --git a/lib/gdlib.php b/lib/gdlib.php
index c384d79f2aa..9c7e50aae8d 100644
--- a/lib/gdlib.php
+++ b/lib/gdlib.php
@@ -216,8 +216,8 @@ function process_new_icon($context, $component, $filearea, $itemid, $originalfil
         $im3 = imagecreate(512, 512);
     }
 
-    $cx = $image->width / 2;
-    $cy = $image->height / 2;
+    $cx = floor($image->width / 2);
+    $cy = floor($image->height / 2);
 
     if ($image->width < $image->height) {
         $half = floor($image->width / 2.0);
diff --git a/mod/bigbluebuttonbn/classes/completion/custom_completion.php b/mod/bigbluebuttonbn/classes/completion/custom_completion.php
index 6f2518eb1be..3de9569e87d 100644
--- a/mod/bigbluebuttonbn/classes/completion/custom_completion.php
+++ b/mod/bigbluebuttonbn/classes/completion/custom_completion.php
@@ -229,7 +229,7 @@ class custom_completion extends activity_custom_completion {
      */
     protected static function get_completionattendance_value(stdClass $log): int {
         $summary = json_decode($log->meta);
-        return empty($summary->data->duration) ? 0 : $summary->data->duration / 60;
+        return empty($summary->data->duration) ? 0 : (int)($summary->data->duration / 60);
     }
 
     /**
diff --git a/mod/h5pactivity/classes/local/attempt.php b/mod/h5pactivity/classes/local/attempt.php
index 0333f766f55..a200db2309e 100644
--- a/mod/h5pactivity/classes/local/attempt.php
+++ b/mod/h5pactivity/classes/local/attempt.php
@@ -493,7 +493,7 @@ class attempt {
      * @return int|null the scaled value
      */
     public function get_scaled(): ?int {
-        return $this->record->scaled;
+        return is_null($this->record->scaled) ? $this->record->scaled : (int)$this->record->scaled;
     }
 
     /**
diff --git a/question/classes/statistics/questions/calculator.php b/question/classes/statistics/questions/calculator.php
index e9afff3d6a9..64a673e4919 100644
--- a/question/classes/statistics/questions/calculator.php
+++ b/question/classes/statistics/questions/calculator.php
@@ -228,8 +228,9 @@ class calculator {
 
                 $this->sumofmarkvariance += $this->stats->for_slot($slot)->markvariance;
 
-                if ($this->stats->for_slot($slot)->covariancewithoverallmark >= 0) {
-                    $sumofcovariancewithoverallmark += sqrt($this->stats->for_slot($slot)->covariancewithoverallmark);
+                $covariancewithoverallmark = $this->stats->for_slot($slot)->covariancewithoverallmark;
+                if (null !== $covariancewithoverallmark && $covariancewithoverallmark >= 0) {
+                    $sumofcovariancewithoverallmark += sqrt($covariancewithoverallmark);
                 }
             }
             $this->progress->end_progress();
diff --git a/question/engine/lib.php b/question/engine/lib.php
index ace64193025..0b06d492005 100644
--- a/question/engine/lib.php
+++ b/question/engine/lib.php
@@ -917,8 +917,8 @@ abstract class question_utils {
                     'converted to roman numerals.', $number);
         }
 
-        return self::$thousands[$number / 1000 % 10] . self::$hundreds[$number / 100 % 10] .
-                self::$tens[$number / 10 % 10] . self::$units[$number % 10];
+        return self::$thousands[floor($number / 1000) % 10] . self::$hundreds[floor($number / 100) % 10] .
+                self::$tens[floor($number / 10) % 10] . self::$units[$number % 10];
     }
 
     /**
diff --git a/question/type/multianswer/renderer.php b/question/type/multianswer/renderer.php
index 27c31e9a6fd..aa4a444bec3 100644
--- a/question/type/multianswer/renderer.php
+++ b/question/type/multianswer/renderer.php
@@ -239,7 +239,7 @@ class qtype_multianswer_textfield_renderer extends qtype_multianswer_subq_render
         foreach ($subq->answers as $ans) {
             $size = max($size, core_text::strlen(trim($ans->answer)));
         }
-        $size = min(60, round($size + rand(0, $size * 0.15)));
+        $size = min(60, round($size + rand(0, (int)($size * 0.15))));
         // The rand bit is to make guessing harder.
 
         $inputattributes = array(
diff --git a/search/classes/engine.php b/search/classes/engine.php
index 367879ecd34..788c27a4f08 100644
--- a/search/classes/engine.php
+++ b/search/classes/engine.php
@@ -307,7 +307,7 @@ abstract class engine {
                 if ($now - $lastprogress >= manager::DISPLAY_INDEXING_PROGRESS_EVERY) {
                     $lastprogress = $now;
                     // The first date format is the same used in cron_trace_time_and_memory().
-                    $options['progress']->output(date('H:i:s', $now) . ': Done to ' . userdate(
+                    $options['progress']->output(date('H:i:s', (int)$now) . ': Done to ' . userdate(
                             $lastindexeddoc, get_string('strftimedatetimeshort', 'langconfig')), 1);
                 }
             }