diff --git a/src/Symfony/Component/BrowserKit/Cookie.php b/src/Symfony/Component/BrowserKit/Cookie.php
index 6afdbd970e91..606478727e2d 100644
--- a/src/Symfony/Component/BrowserKit/Cookie.php
+++ b/src/Symfony/Component/BrowserKit/Cookie.php
@@ -83,6 +83,8 @@ public function __construct(string $name, ?string $value, string $expires = null
 
     /**
      * Returns the HTTP representation of the Cookie.
+     *
+     * @return string
      */
     public function __toString()
     {
diff --git a/src/Symfony/Component/DependencyInjection/Loader/Configurator/ReferenceConfigurator.php b/src/Symfony/Component/DependencyInjection/Loader/Configurator/ReferenceConfigurator.php
index 69e89e11a483..fa042538ce2a 100644
--- a/src/Symfony/Component/DependencyInjection/Loader/Configurator/ReferenceConfigurator.php
+++ b/src/Symfony/Component/DependencyInjection/Loader/Configurator/ReferenceConfigurator.php
@@ -59,6 +59,9 @@ final public function ignoreOnUninitialized(): self
         return $this;
     }
 
+    /**
+     * @return string
+     */
     public function __toString()
     {
         return $this->id;
diff --git a/src/Symfony/Component/DependencyInjection/Variable.php b/src/Symfony/Component/DependencyInjection/Variable.php
index 95e28d60ed30..21d33ebb28fa 100644
--- a/src/Symfony/Component/DependencyInjection/Variable.php
+++ b/src/Symfony/Component/DependencyInjection/Variable.php
@@ -33,6 +33,9 @@ public function __construct(string $name)
         $this->name = $name;
     }
 
+    /**
+     * @return string
+     */
     public function __toString()
     {
         return $this->name;
diff --git a/src/Symfony/Component/ExpressionLanguage/Node/Node.php b/src/Symfony/Component/ExpressionLanguage/Node/Node.php
index 7923cb1d64e4..61bbd0cdae24 100644
--- a/src/Symfony/Component/ExpressionLanguage/Node/Node.php
+++ b/src/Symfony/Component/ExpressionLanguage/Node/Node.php
@@ -33,6 +33,9 @@ public function __construct(array $nodes = [], array $attributes = [])
         $this->attributes = $attributes;
     }
 
+    /**
+     * @return string
+     */
     public function __toString()
     {
         $attributes = [];
diff --git a/src/Symfony/Component/HttpKernel/DataCollector/DataCollector.php b/src/Symfony/Component/HttpKernel/DataCollector/DataCollector.php
index 52ab90c66927..0e040811e1a4 100644
--- a/src/Symfony/Component/HttpKernel/DataCollector/DataCollector.php
+++ b/src/Symfony/Component/HttpKernel/DataCollector/DataCollector.php
@@ -114,6 +114,9 @@ protected function getCasters()
         return $casters;
     }
 
+    /**
+     * @return array
+     */
     public function __sleep()
     {
         if (__CLASS__ !== $c = (new \ReflectionMethod($this, 'serialize'))->getDeclaringClass()->name) {
diff --git a/src/Symfony/Component/HttpKernel/Kernel.php b/src/Symfony/Component/HttpKernel/Kernel.php
index 99c73a9f4b89..55f8467faa06 100644
--- a/src/Symfony/Component/HttpKernel/Kernel.php
+++ b/src/Symfony/Component/HttpKernel/Kernel.php
@@ -870,6 +870,9 @@ public function unserialize($data)
         $this->__construct($environment, $debug);
     }
 
+    /**
+     * @return array
+     */
     public function __sleep()
     {
         if (__CLASS__ !== $c = (new \ReflectionMethod($this, 'serialize'))->getDeclaringClass()->name) {
diff --git a/src/Symfony/Component/HttpKernel/Profiler/Profile.php b/src/Symfony/Component/HttpKernel/Profiler/Profile.php
index f896c00e525e..9de221fc8f91 100644
--- a/src/Symfony/Component/HttpKernel/Profiler/Profile.php
+++ b/src/Symfony/Component/HttpKernel/Profiler/Profile.php
@@ -288,6 +288,9 @@ public function hasCollector($name)
         return isset($this->collectors[$name]);
     }
 
+    /**
+     * @return array
+     */
     public function __sleep()
     {
         return ['token', 'parent', 'children', 'collectors', 'ip', 'method', 'url', 'time', 'statusCode'];
diff --git a/src/Symfony/Component/Mime/Part/DataPart.php b/src/Symfony/Component/Mime/Part/DataPart.php
index 128c53eb6251..423185fef2a9 100644
--- a/src/Symfony/Component/Mime/Part/DataPart.php
+++ b/src/Symfony/Component/Mime/Part/DataPart.php
@@ -125,6 +125,9 @@ public function __destruct()
         }
     }
 
+    /**
+     * @return array
+     */
     public function __sleep()
     {
         // converts the body to a string
diff --git a/src/Symfony/Component/Mime/Part/TextPart.php b/src/Symfony/Component/Mime/Part/TextPart.php
index 77ab98021957..a41d91ddec86 100644
--- a/src/Symfony/Component/Mime/Part/TextPart.php
+++ b/src/Symfony/Component/Mime/Part/TextPart.php
@@ -179,6 +179,9 @@ private function chooseEncoding(): string
         return 'quoted-printable';
     }
 
+    /**
+     * @return array
+     */
     public function __sleep()
     {
         // convert resources to strings for serialization
diff --git a/src/Symfony/Component/VarDumper/Caster/ConstStub.php b/src/Symfony/Component/VarDumper/Caster/ConstStub.php
index 15868b093421..8b0179745f34 100644
--- a/src/Symfony/Component/VarDumper/Caster/ConstStub.php
+++ b/src/Symfony/Component/VarDumper/Caster/ConstStub.php
@@ -26,6 +26,9 @@ public function __construct(string $name, $value = null)
         $this->value = 1 < \func_num_args() ? $value : $name;
     }
 
+    /**
+     * @return string
+     */
     public function __toString()
     {
         return (string) $this->value;
diff --git a/src/Symfony/Component/VarDumper/Cloner/Data.php b/src/Symfony/Component/VarDumper/Cloner/Data.php
index fd7a18a75238..c4dd5eeb4b6d 100644
--- a/src/Symfony/Component/VarDumper/Cloner/Data.php
+++ b/src/Symfony/Component/VarDumper/Cloner/Data.php
@@ -137,6 +137,9 @@ public function __get($key)
         return null;
     }
 
+    /**
+     * @return bool
+     */
     public function __isset($key)
     {
         return null !== $this->seek($key);
@@ -165,6 +168,9 @@ public function offsetUnset($key)
         throw new \BadMethodCallException(self::class.' objects are immutable.');
     }
 
+    /**
+     * @return string
+     */
     public function __toString()
     {
         $value = $this->getValue();