[12.x] Fixes incorrectly serializing virtual properties

.styleci.yml

@@ -4,6 +4,7 @@ php:
   finder:
     not-name:
       - bad-syntax-strategy.php
+      - "*ExcludedFromStyleCiTest.php"
 js:
   finder:
     exclude:

src/Illuminate/Database/Eloquent/Model.php

@@ -2584,18 +2584,25 @@ public function escapeWhenCastingToString($escape = true)
     /**
      * Prepare the object for serialization.
      *
-     * @return array
+     * @return string[]
      */
-    public function __sleep()
+    public function __serialize(): array
     {
         $this->mergeAttributesFromCachedCasts();
 
-        $this->classCastCache = [];
-        $this->attributeCastCache = [];
-        $this->relationAutoloadCallback = null;
-        $this->relationAutoloadContext = null;
+        // When serializing the model, we may accidentally catch up some virtual properties.
+        // We will transform the instance to an array to skip them, and then we will remove
+        // the model caches so those values are not serialized with the rest of the model.
+        $props = get_mangled_object_vars($this);
+
+        unset(
+            $props["\0*\0classCastCache"],
+            $props["\0*\0attributeCastCache"],
+            $props["\0*\0relationAutoloadCallback"],
+            $props["\0*\0relationAutoloadContext"],
+        );
 
-        return array_keys(get_object_vars($this));
+        return $props;
     }
 
     /**

tests/Database/DatabaseEloquentSerializationExcludedFromStyleCiTest.php

@@ -0,0 +1,55 @@
+<?php
+
+namespace Illuminate\Tests\Database;
+
+use PHPUnit\Framework\TestCase;
+
+class DatabaseEloquentSerializationExcludedFromStyleCiTest extends TestCase
+{
+    public function testModelSkipsVirtualPropertiesOnSerialization()
+    {
+        if (version_compare(PHP_VERSION, '8.4.0-dev', '<')) {
+            $this->markTestSkipped('Requires Virtual Properties.');
+        }
+
+        $model = new EloquentModelWithVirtualPropertiesStub();
+        $model->foo = 'bar';
+
+        $serialized = serialize($model);
+
+        $this->assertStringNotContainsString('virtualGet', $serialized);
+        $this->assertStringNotContainsString('virtualSet', $serialized);
+
+        // Ensure attributes and protected normal attributes are also serialized.
+        $this->assertStringContainsString('foo', $serialized);
+        $this->assertStringContainsString('bar', $serialized);
+        $this->assertStringContainsString('isVisible', $serialized);
+        $this->assertStringContainsString('yes', $serialized);
+    }
+}
+
+if (version_compare(PHP_VERSION, '8.4.0-dev', '>=')) {
+    eval(<<<'PHP'
+namespace Illuminate\Tests\Database;
+
+use Illuminate\Database\Eloquent\Model;
+
+class EloquentModelWithVirtualPropertiesStub extends Model
+{
+    public $virtualGet {
+        get => $this->foo;
+    }
+
+    public $virtualSet {
+        get => $this->foo;
+        set {
+            //
+        }
+    }
+
+    protected $isVisible = 'yes';
+}
+
+PHP
+    );
+}