symfony
diff --git a/‎src/Symfony/Component/VarDumper/Caster/ReflectionCaster.php
+17-2 b/‎src/Symfony/Component/VarDumper/Caster/ReflectionCaster.php
+17-2
diff --git a/‎src/Symfony/Component/VarDumper/Tests/Caster/ReflectionCasterTest.php
+22-1 b/‎src/Symfony/Component/VarDumper/Tests/Caster/ReflectionCasterTest.php
+22-1
@@ -299,7 +299,7 @@ public static function castParameter(\ReflectionParameter $c, array $a, Stub $st
             try {
                 $a[$prefix.'default'] = $v = $c->getDefaultValue();
                 if ($c->isDefaultValueConstant() && !\is_object($v)) {
-                    $a[$prefix.'default'] = new ConstStub($c->getDefaultValueConstantName(), $v);
+                    $a[$prefix.'default'] = new ConstStub(self::getDefaultValueConstantName($c), $v);
                 }
                 if (null === $v) {
                     unset($a[$prefix.'allowsNull']);
@@ -383,7 +383,7 @@ public static function getSignature(array $a)
                 $signature .= ' = ';
 
                 if ($param->isDefaultValueConstant()) {
-                    $signature .= substr(strrchr('\\'.$param->getDefaultValueConstantName(), '\\'), 1);
+                    $signature .= substr(strrchr('\\'.self::getDefaultValueConstantName($param), '\\'), 1);
                 } elseif (null === $v) {
                     $signature .= 'null';
                 } elseif (\is_array($v)) {
@@ -445,4 +445,19 @@ private static function addAttributes(array &$a, \Reflector $c, string $prefix =
             }
         }
     }
+
+    private static function getDefaultValueConstantName(\ReflectionParameter $param): ?string
+    {
+        $namespacedConstant = $param->getDefaultValueConstantName();
+
+        if (null !== $namespacedConstant && str_contains($namespacedConstant, '\\') && !\defined($namespacedConstant)) {
+            $globalConstant = '\\'.preg_replace('/^.*\\\\([^\\\\]+)$/', '$1', $namespacedConstant);
+
+            if (\defined($globalConstant) && $param->getDefaultValue() === \constant($globalConstant)) {
+                return $globalConstant;
+            }
+        }
+
+        return $namespacedConstant;
+    }
 }
@@ -13,6 +13,9 @@
 
 use PHPUnit\Framework\TestCase;
 use Symfony\Component\VarDumper\Caster\Caster;
+use Symfony\Component\VarDumper\Caster\ConstStub;
+use Symfony\Component\VarDumper\Caster\ReflectionCaster;
+use Symfony\Component\VarDumper\Cloner\Stub;
 use Symfony\Component\VarDumper\Test\VarDumperTestTrait;
 use Symfony\Component\VarDumper\Tests\Fixtures\ExtendsReflectionTypeFixture;
 use Symfony\Component\VarDumper\Tests\Fixtures\GeneratorDemo;
@@ -95,7 +98,7 @@ public function testClosureCaster()
     $b: & 123
   }
   file: "%sReflectionCasterTest.php"
-  line: "88 to 88"
+  line: "91 to 91"
 }
 EOTXT
             , $var
@@ -701,6 +704,24 @@ public function testReflectionClassConstantWithAttribute()
             , $var);
     }
 
+    public function testGlobalConstantAsDefaultValue()
+    {
+        $class = new class() {
+            public function foo(float $value = M_PI)
+            {
+                // Dummy content
+            }
+        };
+        $method = new \ReflectionMethod($class, 'foo');
+        $parameter = $method->getParameters()[0];
         $cast = ReflectionCaster::castParameter($parameter, [], new Stub(), false);
+        /** @var ConstStub $defaultStub */
+        $defaultStub = $cast["\0~\0default"];
+
+        $this->assertInstanceOf(ConstStub::class, $defaultStub);
+        $this->assertSame('\\'.\M_PI::class, $defaultStub->class);
+    }
+
     /**
      * @requires PHP 8
      */