[VarDumper] Use \ReflectionReference for determining if a key is a reference (php >= 7.4)

src/Symfony/Component/VarDumper/Caster/Caster.php

@@ -68,8 +68,8 @@ public static function castObject($obj, $class, $hasDebugInfo = false)
             foreach ($a as $k => $v) {
                 if (isset($k[0]) ? "\0" !== $k[0] : \PHP_VERSION_ID >= 70200) {
                     if (!isset($publicProperties[$class])) {
-                        foreach (get_class_vars($class) as $prop => $v) {
-                            $publicProperties[$class][$prop] = true;
+                        foreach ((new \ReflectionClass($class))->getProperties(\ReflectionProperty::IS_PUBLIC) as $prop) {
+                            $publicProperties[$class][$prop->name] = true;
                         }
                     }
                     if (!isset($publicProperties[$class][$k])) {

src/Symfony/Component/VarDumper/Cloner/Stub.php

@@ -49,11 +49,17 @@ public function __sleep()
         $properties = [];
 
         if (!isset(self::$defaultProperties[$c = \get_class($this)])) {
-            self::$defaultProperties[$c] = get_class_vars($c);
+            $defaultProperties = get_class_vars($c);
 
-            foreach ((new \ReflectionClass($c))->getStaticProperties() as $k => $v) {
-                unset(self::$defaultProperties[$c][$k]);
+            foreach ((new \ReflectionClass($c))->getProperties(\ReflectionProperty::IS_PUBLIC) as $v) {
+                if ($v->isStatic()) {
+                    unset($defaultProperties[$v->name]);
+                } elseif (!isset($defaultProperties[$v->name])) {
+                    $defaultProperties[$v->name] = null;
+                }
             }
+
+            self::$defaultProperties[$c] = $defaultProperties;
         }
 
         foreach (self::$defaultProperties[$c] as $k => $v) {

src/Symfony/Component/VarDumper/Cloner/VarCloner.php

@@ -42,7 +42,7 @@ protected function doClone($var)
         $currentDepth = 0;              // Current tree depth
         $currentDepthFinalIndex = 0;    // Final $queue index for current tree depth
         $minimumDepthReached = 0 === $minDepth; // Becomes true when minimum tree depth has been reached
-        $cookie = (object) [];     // Unique object used to detect hard references
+        $cookie = (object) [];          // Unique object used to detect hard references
         $a = null;                      // Array cast for nested structures
         $stub = null;                   // Stub capturing the main properties of an original item value
                                         // or null if the original value is used directly
@@ -86,8 +86,15 @@ protected function doClone($var)
             }
             foreach ($vals as $k => $v) {
                 // $v is the original value or a stub object in case of hard references
-                $refs[$k] = $cookie;
-                if ($zvalIsRef = $vals[$k] === $cookie) {
+
+                if (\PHP_VERSION_ID >= 70400) {
+                    $zvalIsRef = null !== \ReflectionReference::fromArrayElement($vals, $k);
+                } else {
+                    $refs[$k] = $cookie;
+                    $zvalIsRef = $vals[$k] === $cookie;
+                }
+
+                if ($zvalIsRef) {
                     $vals[$k] = &$stub;         // Break hard references to make $queue completely
                     unset($stub);               // independent from the original structure
                     if ($v instanceof Stub && isset($hardRefs[spl_object_hash($v)])) {

src/Symfony/Component/VarDumper/Tests/Cloner/VarClonerTest.php

@@ -13,6 +13,7 @@
 
 use PHPUnit\Framework\TestCase;
 use Symfony\Component\VarDumper\Cloner\VarCloner;
+use Symfony\Component\VarDumper\Tests\Fixtures\Php74;
 
 /**
  * @author Nicolas Grekas <p@tchwork.com>
@@ -431,6 +432,73 @@ public function testCaster()
     [useRefHandles:Symfony\Component\VarDumper\Cloner\Data:private] => -1
 )
 
+EOTXT;
+        $this->assertStringMatchesFormat($expected, print_r($clone, true));
+    }
+
+    /**
+     * @requires PHP 7.4
+     */
+    public function testPhp74()
+    {
+        $data = new Php74();
+
+        $cloner = new VarCloner();
+        $clone = $cloner->cloneVar($data);
+
+        $expected = <<<'EOTXT'
+Symfony\Component\VarDumper\Cloner\Data Object
+(
+    [data:Symfony\Component\VarDumper\Cloner\Data:private] => Array
+        (
+            [0] => Array
+                (
+                    [0] => Symfony\Component\VarDumper\Cloner\Stub Object
+                        (
+                            [type] => 4
+                            [class] => Symfony\Component\VarDumper\Tests\Fixtures\Php74
+                            [value] => 
+                            [cut] => 0
+                            [handle] => %i
+                            [refCount] => 0
+                            [position] => 1
+                            [attr] => Array
+                                (
+                                )
+
+                        )
+
+                )
+
+            [1] => Array
+                (
+                    [p1] => 123
+                    [p2] => Symfony\Component\VarDumper\Cloner\Stub Object
+                        (
+                            [type] => 4
+                            [class] => stdClass
+                            [value] => 
+                            [cut] => 0
+                            [handle] => %i
+                            [refCount] => 0
+                            [position] => 0
+                            [attr] => Array
+                                (
+                                )
+
+                        )
+
+                )
+
+        )
+
+    [position:Symfony\Component\VarDumper\Cloner\Data:private] => 0
+    [key:Symfony\Component\VarDumper\Cloner\Data:private] => 0
+    [maxDepth:Symfony\Component\VarDumper\Cloner\Data:private] => 20
+    [maxItemsPerDepth:Symfony\Component\VarDumper\Cloner\Data:private] => -1
+    [useRefHandles:Symfony\Component\VarDumper\Cloner\Data:private] => -1
+)
+
 EOTXT;
         $this->assertStringMatchesFormat($expected, print_r($clone, true));
     }

src/Symfony/Component/VarDumper/Tests/Fixtures/Php74.php

@@ -0,0 +1,14 @@
+<?php
+
+namespace Symfony\Component\VarDumper\Tests\Fixtures;
+
+class Php74
+{
+    public $p1 = 123;
+    public \stdClass $p2;
+
+    public function __construct()
+    {
+        $this->p2 = new \stdClass();
+    }
+}