bug #37860 [Serializer][ClassDiscriminatorMapping] Fix getMappedObjectType() when a discriminator child extends another one (fancyweb)

This PR was merged into the 4.4 branch.

Discussion
----------

[Serializer][ClassDiscriminatorMapping] Fix getMappedObjectType() when a discriminator child extends another one

| Q             | A
| ------------- | ---
| Branch?       | 4.4
| Bug fix?      | yes
| New feature?  | no
| Deprecations? | no
| Tickets       | https://github.com/symfony/symfony/issues/37742
| License       | MIT
| Doc PR        | -

The strategy is to sort the passed classes from the "bottom" one in the hierarchy to the "top" one so that the first `is_a` in `getMappedObjectType()` is right.

Commits
-------

c16a192473 [Serializer][ClassDiscriminatorMapping] Fix getMappedObjectType() when a discriminator child extends another one

src/Symfony/Component/Serializer/Mapping/ClassDiscriminatorMapping.php

@@ -23,6 +23,18 @@ class ClassDiscriminatorMapping
     {
         $this->typeProperty = $typeProperty;
         $this->typesMapping = $typesMapping;
+
+        uasort($this->typesMapping, static function (string $a, string $b): int {
+            if (is_a($a, $b, true)) {
+                return -1;
+            }
+
+            if (is_a($b, $a, true)) {
+                return 1;
+            }
+
+            return 0;
+        });
     }
 
     public function getTypeProperty(): string

src/Symfony/Component/Serializer/Tests/Fixtures/AbstractDummy.php

@@ -16,7 +16,8 @@ use Symfony\Component\Serializer\Annotation\DiscriminatorMap;
 /**
  * @DiscriminatorMap(typeProperty="type", mapping={
  *    "first"="Symfony\Component\Serializer\Tests\Fixtures\AbstractDummyFirstChild",
- *    "second"="Symfony\Component\Serializer\Tests\Fixtures\AbstractDummySecondChild"
+ *    "second"="Symfony\Component\Serializer\Tests\Fixtures\AbstractDummySecondChild",
+ *    "third"="Symfony\Component\Serializer\Tests\Fixtures\AbstractDummyThirdChild",
  * })
  */
 abstract class AbstractDummy

src/Symfony/Component/Serializer/Tests/Fixtures/AbstractDummyThirdChild.php

@@ -0,0 +1,16 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Symfony\Component\Serializer\Tests\Fixtures;
+
+final class AbstractDummyThirdChild extends AbstractDummyFirstChild
+{
+}

src/Symfony/Component/Serializer/Tests/Mapping/ClassDiscriminatorMappingTest.php

@@ -15,6 +15,7 @@ use PHPUnit\Framework\TestCase;
 use Symfony\Component\Serializer\Mapping\ClassDiscriminatorMapping;
 use Symfony\Component\Serializer\Tests\Fixtures\AbstractDummyFirstChild;
 use Symfony\Component\Serializer\Tests\Fixtures\AbstractDummySecondChild;
+use Symfony\Component\Serializer\Tests\Fixtures\AbstractDummyThirdChild;
 
 /**
  * @author Samuel Roze <samuel.roze@gmail.com>
@@ -35,9 +36,11 @@ class ClassDiscriminatorMappingTest extends TestCase
     {
         $mapping = new ClassDiscriminatorMapping('type', [
             'first' => AbstractDummyFirstChild::class,
+            'third' => AbstractDummyThirdChild::class,
         ]);
 
         $this->assertEquals('first', $mapping->getMappedObjectType(new AbstractDummyFirstChild()));
         $this->assertNull($mapping->getMappedObjectType(new AbstractDummySecondChild()));
+        $this->assertSame('third', $mapping->getMappedObjectType(new AbstractDummyThirdChild()));
     }
 }

src/Symfony/Component/Serializer/Tests/Mapping/Loader/AnnotationLoaderTest.php

@@ -20,6 +20,7 @@ use Symfony\Component\Serializer\Mapping\Loader\AnnotationLoader;
 use Symfony\Component\Serializer\Tests\Fixtures\AbstractDummy;
 use Symfony\Component\Serializer\Tests\Fixtures\AbstractDummyFirstChild;
 use Symfony\Component\Serializer\Tests\Fixtures\AbstractDummySecondChild;
+use Symfony\Component\Serializer\Tests\Fixtures\AbstractDummyThirdChild;
 use Symfony\Component\Serializer\Tests\Mapping\TestClassMetadataFactory;
 
 /**
@@ -65,6 +66,7 @@ class AnnotationLoaderTest extends TestCase
         $expected = new ClassMetadata(AbstractDummy::class, new ClassDiscriminatorMapping('type', [
             'first' => AbstractDummyFirstChild::class,
             'second' => AbstractDummySecondChild::class,
+            'third' => AbstractDummyThirdChild::class,
         ]));
 
         $expected->addAttributeMetadata(new AttributeMetadata('foo'));