build: add Rector

composer.json

@@ -28,9 +28,9 @@
         "dealerdirect/phpcodesniffer-composer-installer": "^0.7.1",
         "phpcompatibility/php-compatibility": "*",
         "wp-coding-standards/wpcs": "^2.3",
-        "phpdocumentor/phpdocumentor": "^3.0",
         "marcocesarato/php-conventional-changelog": "^1.9",
-        "phpcompatibility/phpcompatibility-wp": "*"
+        "phpcompatibility/phpcompatibility-wp": "*",
+        "rector/rector": "^0.10.16"
     },
     "prefer-stable": true
 }

rector.php

@@ -0,0 +1,30 @@
+<?php
+
+declare(strict_types=1);
+
+use Rector\Core\Configuration\Option;
+use Rector\Set\ValueObject\SetList;
+use Rector\Set\ValueObject\DowngradeSetList;
+use Rector\Core\ValueObject\PhpVersion;
+use Symfony\Component\DependencyInjection\Loader\Configurator\ContainerConfigurator;
+
+return static function (ContainerConfigurator $containerConfigurator): void {
+    // get parameters
+    $parameters = $containerConfigurator->parameters();
+    
+    $parameters->set(Option::PATHS, [
+        __DIR__ . '/src',
+    ]);
+
+    // Define what rule sets will be applied
+    $parameters->set(Option::SETS, [
+       // SetList::CODE_QUALITY,
+        SetList::DEAD_CODE,
+       // DowngradeSetList::PHP_80,
+       // DowngradeSetList::PHP_74,
+       // DowngradeSetList::PHP_73,
+        //DowngradeSetList::PHP_72,
+    ]);
+
+    $parameters->set(Option::PHP_VERSION_FEATURES, PhpVersion::PHP_71);
+};