diff --git a/framework/base/DynamicContentAwareTrait.php b/framework/base/DynamicContentAwareTrait.php
index d175936cc7..b19382e93e 100644
--- a/framework/base/DynamicContentAwareTrait.php
+++ b/framework/base/DynamicContentAwareTrait.php
@@ -72,8 +72,9 @@ trait DynamicContentAwareTrait
             $content = strtr($content, $placeholders);
         }
         if ($isRestoredFromCache) {
+            $view = $this->getView();
             foreach ($placeholders as $name => $statements) {
-                $this->getView()->addDynamicPlaceholder($name, $statements);
+                $view->addDynamicPlaceholder($name, $statements);
             }
         }
 
diff --git a/framework/captcha/CaptchaAction.php b/framework/captcha/CaptchaAction.php
index a1aebb81d4..3ded638459 100644
--- a/framework/captcha/CaptchaAction.php
+++ b/framework/captcha/CaptchaAction.php
@@ -191,7 +191,7 @@ class CaptchaAction extends Action
         $session = Yii::$app->getSession();
         $session->open();
         $name = $this->getSessionKey() . 'count';
-        $session[$name] = $session[$name] + 1;
+        $session[$name] += 1;
         if ($valid || $session[$name] > $this->testLimit && $this->testLimit > 0) {
             $this->getVerifyCode(true);
         }
diff --git a/framework/db/Connection.php b/framework/db/Connection.php
index 5bc06d0106..29ad0c3507 100644
--- a/framework/db/Connection.php
+++ b/framework/db/Connection.php
@@ -1025,7 +1025,7 @@ class Connection extends Component
     public function getMaster()
     {
         if ($this->_master === false) {
-            $this->_master = ($this->shuffleMasters)
+            $this->_master = $this->shuffleMasters
                 ? $this->openFromPool($this->masters, $this->masterConfig)
                 : $this->openFromPoolSequentially($this->masters, $this->masterConfig);
         }
diff --git a/framework/db/Query.php b/framework/db/Query.php
index ad9e1bc614..3bc6333ba9 100644
--- a/framework/db/Query.php
+++ b/framework/db/Query.php
@@ -668,7 +668,7 @@ PATTERN;
                     if ($existsInSelect) {
                         continue;
                     }
-                } elseif (is_integer($columnAlias)) {
+                } elseif (is_int($columnAlias)) {
                     $existsInSelect = in_array($columnDefinition, $unaliasedColumns, true);
                     $existsInResultSet = in_array($columnDefinition, $result, true);
                     if ($existsInSelect || $existsInResultSet) {
@@ -691,7 +691,7 @@ PATTERN;
         $result = [];
         if (is_array($this->select)) {
             foreach ($this->select as $name => $value) {
-                if (is_integer($name)) {
+                if (is_int($name)) {
                     $result[] = $value;
                 }
             }
diff --git a/framework/helpers/BaseArrayHelper.php b/framework/helpers/BaseArrayHelper.php
index fac597fb17..e40929dfe4 100644
--- a/framework/helpers/BaseArrayHelper.php
+++ b/framework/helpers/BaseArrayHelper.php
@@ -938,7 +938,7 @@ class BaseArrayHelper
                 continue;
             }
 
-            if (!key_exists($globalKey, $array)) {
+            if (!array_key_exists($globalKey, $array)) {
                 continue;
             }
             if ($localKey === null) {
diff --git a/framework/helpers/BaseFileHelper.php b/framework/helpers/BaseFileHelper.php
index a4d58d03c9..3a51d431db 100644
--- a/framework/helpers/BaseFileHelper.php
+++ b/framework/helpers/BaseFileHelper.php
@@ -367,7 +367,7 @@ class BaseFileHelper
         if (!is_dir($dir)) {
             return;
         }
-        if (isset($options['traverseSymlinks']) && $options['traverseSymlinks'] || !is_link($dir)) {
+        if (!empty($options['traverseSymlinks']) || !is_link($dir)) {
             if (!($handle = opendir($dir))) {
                 return;
             }
diff --git a/framework/i18n/Formatter.php b/framework/i18n/Formatter.php
index 01e61428ec..cc1929db9b 100644
--- a/framework/i18n/Formatter.php
+++ b/framework/i18n/Formatter.php
@@ -1624,7 +1624,7 @@ class Formatter extends Component
                 if (abs($value) < $formatBase) {
                     break;
                 }
-                $value = $value / $formatBase;
+                $value /= $formatBase;
             }
             $position++;
         } while ($position < $maxPosition + 1);
diff --git a/framework/rest/OptionsAction.php b/framework/rest/OptionsAction.php
index 5ce6d8fdc9..b6b8b5762b 100644
--- a/framework/rest/OptionsAction.php
+++ b/framework/rest/OptionsAction.php
@@ -39,7 +39,8 @@ class OptionsAction extends \yii\base\Action
             Yii::$app->getResponse()->setStatusCode(405);
         }
         $options = $id === null ? $this->collectionOptions : $this->resourceOptions;
-        Yii::$app->getResponse()->getHeaders()->set('Allow', implode(', ', $options));
-        Yii::$app->getResponse()->getHeaders()->set('Access-Control-Allow-Method', implode(', ', $options));
+        $headers = Yii::$app->getResponse()->getHeaders();
+        $headers->set('Allow', implode(', ', $options));
+        $headers->set('Access-Control-Allow-Method', implode(', ', $options));
     }
 }
diff --git a/framework/validators/NumberValidator.php b/framework/validators/NumberValidator.php
index 88b0d4165f..3610899bce 100644
--- a/framework/validators/NumberValidator.php
+++ b/framework/validators/NumberValidator.php
@@ -125,7 +125,7 @@ class NumberValidator extends Validator
     {
         return is_array($value)
         || (is_object($value) && !method_exists($value, '__toString'))
-        || (!is_object($value) && !is_scalar($value) && !is_null($value));
+        || (!is_object($value) && !is_scalar($value) && $value !== null);
     }
 
     /**
diff --git a/framework/web/Request.php b/framework/web/Request.php
index f257902d93..7173999135 100644
--- a/framework/web/Request.php
+++ b/framework/web/Request.php
@@ -1196,7 +1196,7 @@ class Request extends \yii\base\Request
          * RewriteRule .* - [E=HTTP_AUTHORIZATION:%{HTTP:Authorization}]
          */
         $auth_token = $this->getHeaders()->get('HTTP_AUTHORIZATION') ?: $this->getHeaders()->get('REDIRECT_HTTP_AUTHORIZATION');
-        if ($auth_token !== null && strpos(strtolower($auth_token), 'basic') === 0) {
+        if ($auth_token !== null && stripos($auth_token, 'basic') === 0) {
             $parts = array_map(function ($value) {
                 return strlen($value) === 0 ? null : $value;
             }, explode(':', base64_decode(mb_substr($auth_token, 6)), 2));