diff --git a/src/Symfony/Component/Debug/README.md b/src/Symfony/Component/Debug/README.md
index 7c7bbe8b8e..90b36f0cb8 100644
--- a/src/Symfony/Component/Debug/README.md
+++ b/src/Symfony/Component/Debug/README.md
@@ -8,6 +8,19 @@ Debug Component
 
 The Debug component provides tools to ease debugging PHP code.
 
+Getting Started
+---------------
+
+```
+$ composer install symfony/debug
+```
+
+```php
+use Symfony\Component\Debug\Debug;
+
+Debug::enable();
+```
+
 Resources
 ---------
 
diff --git a/src/Symfony/Component/Form/Extension/Core/Type/DateTimeType.php b/src/Symfony/Component/Form/Extension/Core/Type/DateTimeType.php
index 3f27bced3f..0959ee7d32 100644
--- a/src/Symfony/Component/Form/Extension/Core/Type/DateTimeType.php
+++ b/src/Symfony/Component/Form/Extension/Core/Type/DateTimeType.php
@@ -108,7 +108,17 @@ class DateTimeType extends AbstractType
                 'invalid_message_parameters',
             ]));
 
-            if (isset($emptyData['date'])) {
+            if ($emptyData instanceof \Closure) {
+                $lazyEmptyData = static function ($option) use ($emptyData) {
+                    return static function (FormInterface $form) use ($emptyData, $option) {
+                        $emptyData = $emptyData($form->getParent());
+
+                        return isset($emptyData[$option]) ? $emptyData[$option] : '';
+                    };
+                };
+
+                $dateOptions['empty_data'] = $lazyEmptyData('date');
+            } elseif (isset($emptyData['date'])) {
                 $dateOptions['empty_data'] = $emptyData['date'];
             }
 
@@ -127,7 +137,9 @@ class DateTimeType extends AbstractType
                 'invalid_message_parameters',
             ]));
 
-            if (isset($emptyData['time'])) {
+            if ($emptyData instanceof \Closure) {
+                $timeOptions['empty_data'] = $lazyEmptyData('time');
+            } elseif (isset($emptyData['time'])) {
                 $timeOptions['empty_data'] = $emptyData['time'];
             }
 
diff --git a/src/Symfony/Component/Form/Extension/Core/Type/DateType.php b/src/Symfony/Component/Form/Extension/Core/Type/DateType.php
index d9389db69a..58c4bbcf33 100644
--- a/src/Symfony/Component/Form/Extension/Core/Type/DateType.php
+++ b/src/Symfony/Component/Form/Extension/Core/Type/DateType.php
@@ -82,14 +82,28 @@ class DateType extends AbstractType
             // so we need to handle the cascade setting here
             $emptyData = $builder->getEmptyData() ?: [];
 
-            if (isset($emptyData['year'])) {
-                $yearOptions['empty_data'] = $emptyData['year'];
-            }
-            if (isset($emptyData['month'])) {
-                $monthOptions['empty_data'] = $emptyData['month'];
-            }
-            if (isset($emptyData['day'])) {
-                $dayOptions['empty_data'] = $emptyData['day'];
+            if ($emptyData instanceof \Closure) {
+                $lazyEmptyData = static function ($option) use ($emptyData) {
+                    return static function (FormInterface $form) use ($emptyData, $option) {
+                        $emptyData = $emptyData($form->getParent());
+
+                        return isset($emptyData[$option]) ? $emptyData[$option] : '';
+                    };
+                };
+
+                $yearOptions['empty_data'] = $lazyEmptyData('year');
+                $monthOptions['empty_data'] = $lazyEmptyData('month');
+                $dayOptions['empty_data'] = $lazyEmptyData('day');
+            } else {
+                if (isset($emptyData['year'])) {
+                    $yearOptions['empty_data'] = $emptyData['year'];
+                }
+                if (isset($emptyData['month'])) {
+                    $monthOptions['empty_data'] = $emptyData['month'];
+                }
+                if (isset($emptyData['day'])) {
+                    $dayOptions['empty_data'] = $emptyData['day'];
+                }
             }
 
             if (isset($options['invalid_message'])) {
diff --git a/src/Symfony/Component/Form/Extension/Core/Type/TimeType.php b/src/Symfony/Component/Form/Extension/Core/Type/TimeType.php
index 053f774fa8..7475b09b2e 100644
--- a/src/Symfony/Component/Form/Extension/Core/Type/TimeType.php
+++ b/src/Symfony/Component/Form/Extension/Core/Type/TimeType.php
@@ -93,7 +93,17 @@ class TimeType extends AbstractType
             // so we need to handle the cascade setting here
             $emptyData = $builder->getEmptyData() ?: [];
 
-            if (isset($emptyData['hour'])) {
+            if ($emptyData instanceof \Closure) {
+                $lazyEmptyData = static function ($option) use ($emptyData) {
+                    return static function (FormInterface $form) use ($emptyData, $option) {
+                        $emptyData = $emptyData($form->getParent());
+
+                        return isset($emptyData[$option]) ? $emptyData[$option] : '';
+                    };
+                };
+
+                $hourOptions['empty_data'] = $lazyEmptyData('hour');
+            } elseif (isset($emptyData['hour'])) {
                 $hourOptions['empty_data'] = $emptyData['hour'];
             }
 
@@ -160,14 +170,18 @@ class TimeType extends AbstractType
             $builder->add('hour', self::$widgets[$options['widget']], $hourOptions);
 
             if ($options['with_minutes']) {
-                if (isset($emptyData['minute'])) {
+                if ($emptyData instanceof \Closure) {
+                    $minuteOptions['empty_data'] = $lazyEmptyData('minute');
+                } elseif (isset($emptyData['minute'])) {
                     $minuteOptions['empty_data'] = $emptyData['minute'];
                 }
                 $builder->add('minute', self::$widgets[$options['widget']], $minuteOptions);
             }
 
             if ($options['with_seconds']) {
-                if (isset($emptyData['second'])) {
+                if ($emptyData instanceof \Closure) {
+                    $secondOptions['empty_data'] = $lazyEmptyData('second');
+                } elseif (isset($emptyData['second'])) {
                     $secondOptions['empty_data'] = $emptyData['second'];
                 }
                 $builder->add('second', self::$widgets[$options['widget']], $secondOptions);
diff --git a/src/Symfony/Component/Form/Tests/Extension/Core/Type/DateTimeTypeTest.php b/src/Symfony/Component/Form/Tests/Extension/Core/Type/DateTimeTypeTest.php
index c1690222b8..b0c4f35492 100644
--- a/src/Symfony/Component/Form/Tests/Extension/Core/Type/DateTimeTypeTest.php
+++ b/src/Symfony/Component/Form/Tests/Extension/Core/Type/DateTimeTypeTest.php
@@ -12,6 +12,7 @@
 namespace Symfony\Component\Form\Tests\Extension\Core\Type;
 
 use Symfony\Component\Form\FormError;
+use Symfony\Component\Form\FormInterface;
 
 class DateTimeTypeTest extends BaseTypeTest
 {
@@ -671,6 +672,9 @@ class DateTimeTypeTest extends BaseTypeTest
         ]);
         $form->submit(null);
 
+        if ($emptyData instanceof \Closure) {
+            $emptyData = $emptyData($form);
+        }
         $this->assertSame($emptyData, $form->getViewData());
         $this->assertEquals($expectedData, $form->getNormData());
         $this->assertEquals($expectedData, $form->getData());
@@ -679,11 +683,17 @@ class DateTimeTypeTest extends BaseTypeTest
     public function provideEmptyData()
     {
         $expectedData = \DateTime::createFromFormat('Y-m-d H:i', '2018-11-11 21:23');
+        $lazyEmptyData = static function (FormInterface $form) {
+            return $form->getConfig()->getCompound() ? ['date' => ['year' => '2018', 'month' => '11', 'day' => '11'], 'time' => ['hour' => '21', 'minute' => '23']] : '2018-11-11T21:23:00';
+        };
 
         return [
             'Simple field' => ['single_text', '2018-11-11T21:23:00', $expectedData],
             'Compound text field' => ['text', ['date' => ['year' => '2018', 'month' => '11', 'day' => '11'], 'time' => ['hour' => '21', 'minute' => '23']], $expectedData],
             'Compound choice field' => ['choice', ['date' => ['year' => '2018', 'month' => '11', 'day' => '11'], 'time' => ['hour' => '21', 'minute' => '23']], $expectedData],
+            'Simple field lazy' => ['single_text', $lazyEmptyData, $expectedData],
+            'Compound text field lazy' => ['text', $lazyEmptyData, $expectedData],
+            'Compound choice field lazy' => ['choice', $lazyEmptyData, $expectedData],
         ];
     }
 
diff --git a/src/Symfony/Component/Form/Tests/Extension/Core/Type/DateTypeTest.php b/src/Symfony/Component/Form/Tests/Extension/Core/Type/DateTypeTest.php
index 62588011da..a281215fd4 100644
--- a/src/Symfony/Component/Form/Tests/Extension/Core/Type/DateTypeTest.php
+++ b/src/Symfony/Component/Form/Tests/Extension/Core/Type/DateTypeTest.php
@@ -13,6 +13,7 @@ namespace Symfony\Component\Form\Tests\Extension\Core\Type;
 
 use Symfony\Component\Form\ChoiceList\View\ChoiceView;
 use Symfony\Component\Form\FormError;
+use Symfony\Component\Form\FormInterface;
 use Symfony\Component\Intl\Util\IntlTestHelper;
 
 class DateTypeTest extends BaseTypeTest
@@ -1022,6 +1023,9 @@ class DateTypeTest extends BaseTypeTest
         ]);
         $form->submit(null);
 
+        if ($emptyData instanceof \Closure) {
+            $emptyData = $emptyData($form);
+        }
         $this->assertSame($emptyData, $form->getViewData());
         $this->assertEquals($expectedData, $form->getNormData());
         $this->assertEquals($expectedData, $form->getData());
@@ -1030,11 +1034,17 @@ class DateTypeTest extends BaseTypeTest
     public function provideEmptyData()
     {
         $expectedData = \DateTime::createFromFormat('Y-m-d H:i:s', '2018-11-11 00:00:00');
+        $lazyEmptyData = static function (FormInterface $form) {
+            return $form->getConfig()->getCompound() ? ['year' => '2018', 'month' => '11', 'day' => '11'] : '2018-11-11';
+        };
 
         return [
             'Simple field' => ['single_text', '2018-11-11', $expectedData],
             'Compound text fields' => ['text', ['year' => '2018', 'month' => '11', 'day' => '11'], $expectedData],
             'Compound choice fields' => ['choice', ['year' => '2018', 'month' => '11', 'day' => '11'], $expectedData],
+            'Simple field lazy' => ['single_text', $lazyEmptyData, $expectedData],
+            'Compound text fields lazy' => ['text', $lazyEmptyData, $expectedData],
+            'Compound choice fields lazy' => ['choice', $lazyEmptyData, $expectedData],
         ];
     }
 
diff --git a/src/Symfony/Component/Form/Tests/Extension/Core/Type/TimeTypeTest.php b/src/Symfony/Component/Form/Tests/Extension/Core/Type/TimeTypeTest.php
index dcbfaf8615..645c5b9ede 100644
--- a/src/Symfony/Component/Form/Tests/Extension/Core/Type/TimeTypeTest.php
+++ b/src/Symfony/Component/Form/Tests/Extension/Core/Type/TimeTypeTest.php
@@ -13,6 +13,7 @@ namespace Symfony\Component\Form\Tests\Extension\Core\Type;
 
 use Symfony\Component\Form\ChoiceList\View\ChoiceView;
 use Symfony\Component\Form\FormError;
+use Symfony\Component\Form\FormInterface;
 
 class TimeTypeTest extends BaseTypeTest
 {
@@ -929,6 +930,9 @@ class TimeTypeTest extends BaseTypeTest
         ]);
         $form->submit(null);
 
+        if ($emptyData instanceof \Closure) {
+            $emptyData = $emptyData($form);
+        }
         $this->assertSame($emptyData, $form->getViewData());
         $this->assertEquals($expectedData, $form->getNormData());
         $this->assertEquals($expectedData, $form->getData());
@@ -937,11 +941,17 @@ class TimeTypeTest extends BaseTypeTest
     public function provideEmptyData()
     {
         $expectedData = \DateTime::createFromFormat('Y-m-d H:i', '1970-01-01 21:23');
+        $lazyEmptyData = static function (FormInterface $form) {
+            return $form->getConfig()->getCompound() ? ['hour' => '21', 'minute' => '23'] : '21:23';
+        };
 
         return [
             'Simple field' => ['single_text', '21:23', $expectedData],
             'Compound text field' => ['text', ['hour' => '21', 'minute' => '23'], $expectedData],
             'Compound choice field' => ['choice', ['hour' => '21', 'minute' => '23'], $expectedData],
+            'Simple field lazy' => ['single_text', $lazyEmptyData, $expectedData],
+            'Compound text field lazy' => ['text', $lazyEmptyData, $expectedData],
+            'Compound choice field lazy' => ['choice', $lazyEmptyData, $expectedData],
         ];
     }
 }
diff --git a/src/Symfony/Component/Translation/README.md b/src/Symfony/Component/Translation/README.md
index e80a70cad0..f4f1706675 100644
--- a/src/Symfony/Component/Translation/README.md
+++ b/src/Symfony/Component/Translation/README.md
@@ -3,10 +3,28 @@ Translation Component
 
 The Translation component provides tools to internationalize your application.
 
+Getting Started
+---------------
+
+```
+$ composer require symfony/translation
+```
+
+```php
+use Symfony\Component\Translation\Translator;
+
+$translator = new Translator('fr_FR');
+$translator->addResource('array', [
+    'Hello World!' => 'Bonjour !',
+], 'fr_FR');
+
+echo $translator->trans('Hello World!'); // outputs « Bonjour ! »
+```
+
 Resources
 ---------
 
-  * [Documentation](https://symfony.com/doc/current/components/translation.html)
+  * [Documentation](https://symfony.com/doc/current/translation.html)
   * [Contributing](https://symfony.com/doc/current/contributing/index.html)
   * [Report issues](https://github.com/symfony/symfony/issues) and
     [send Pull Requests](https://github.com/symfony/symfony/pulls)
diff --git a/src/Symfony/Component/Validator/Mapping/PropertyMetadata.php b/src/Symfony/Component/Validator/Mapping/PropertyMetadata.php
index 2a8d3f4f56..23c0f73562 100644
--- a/src/Symfony/Component/Validator/Mapping/PropertyMetadata.php
+++ b/src/Symfony/Component/Validator/Mapping/PropertyMetadata.php
@@ -50,8 +50,21 @@ class PropertyMetadata extends MemberMetadata
     {
         $reflProperty = $this->getReflectionMember($object);
 
-        if (\PHP_VERSION_ID >= 70400 && !$reflProperty->isInitialized($object)) {
-            return null;
+        if (\PHP_VERSION_ID >= 70400 && $reflProperty->hasType() && !$reflProperty->isInitialized($object)) {
+            // There is no way to check if a property has been unset or if it is uninitialized.
+            // When trying to access an uninitialized property, __get method is triggered.
+
+            // If __get method is not present, no fallback is possible
+            // Otherwise we need to catch an Error in case we are trying to access an uninitialized but set property.
+            if (!method_exists($object, '__get')) {
+                return null;
+            }
+
+            try {
+                return $reflProperty->getValue($object);
+            } catch (\Error $e) {
+                return null;
+            }
         }
 
         return $reflProperty->getValue($object);
diff --git a/src/Symfony/Component/Validator/Tests/Fixtures/Entity_74_Proxy.php b/src/Symfony/Component/Validator/Tests/Fixtures/Entity_74_Proxy.php
new file mode 100644
index 0000000000..d74badc7d7
--- /dev/null
+++ b/src/Symfony/Component/Validator/Tests/Fixtures/Entity_74_Proxy.php
@@ -0,0 +1,18 @@
+<?php
+
+namespace Symfony\Component\Validator\Tests\Fixtures;
+
+class Entity_74_Proxy extends Entity_74
+{
+    public string $notUnset;
+
+    public function __construct()
+    {
+        unset($this->uninitialized);
+    }
+
+    public function __get($name)
+    {
+        return 42;
+    }
+}
diff --git a/src/Symfony/Component/Validator/Tests/Mapping/PropertyMetadataTest.php b/src/Symfony/Component/Validator/Tests/Mapping/PropertyMetadataTest.php
index 8d9e67881a..8868ec64aa 100644
--- a/src/Symfony/Component/Validator/Tests/Mapping/PropertyMetadataTest.php
+++ b/src/Symfony/Component/Validator/Tests/Mapping/PropertyMetadataTest.php
@@ -15,11 +15,13 @@ use PHPUnit\Framework\TestCase;
 use Symfony\Component\Validator\Mapping\PropertyMetadata;
 use Symfony\Component\Validator\Tests\Fixtures\Entity;
 use Symfony\Component\Validator\Tests\Fixtures\Entity_74;
+use Symfony\Component\Validator\Tests\Fixtures\Entity_74_Proxy;
 
 class PropertyMetadataTest extends TestCase
 {
     const CLASSNAME = 'Symfony\Component\Validator\Tests\Fixtures\Entity';
     const CLASSNAME_74 = 'Symfony\Component\Validator\Tests\Fixtures\Entity_74';
+    const CLASSNAME_74_PROXY = 'Symfony\Component\Validator\Tests\Fixtures\Entity_74_Proxy';
     const PARENTCLASS = 'Symfony\Component\Validator\Tests\Fixtures\EntityParent';
 
     public function testInvalidPropertyName()
@@ -66,4 +68,17 @@ class PropertyMetadataTest extends TestCase
 
         $this->assertNull($metadata->getPropertyValue($entity));
     }
+
+    /**
+     * @requires PHP 7.4
+     */
+    public function testGetPropertyValueFromUninitializedPropertyShouldNotReturnNullIfMagicGetIsPresent()
+    {
+        $entity = new Entity_74_Proxy();
+        $metadata = new PropertyMetadata(self::CLASSNAME_74_PROXY, 'uninitialized');
+        $notUnsetMetadata = new PropertyMetadata(self::CLASSNAME_74_PROXY, 'notUnset');
+
+        $this->assertNull($notUnsetMetadata->getPropertyValue($entity));
+        $this->assertEquals(42, $metadata->getPropertyValue($entity));
+    }
 }