ContainerBuilder::addDefinition(null) adds anonymous service

src/DI/ContainerBuilder.php

@@ -56,8 +56,15 @@ class ContainerBuilder
 	/**
 	 * Adds new service definition.
 	 */
-	public function addDefinition(string $name, ServiceDefinition $definition = null): ServiceDefinition
+	public function addDefinition(?string $name, ServiceDefinition $definition = null): ServiceDefinition
 	{
+		if ($name === null) {
+			$name = count($this->definitions) + 1;
+			while (isset($this->definitions[$name])) {
+				$name++;
+			}
+		}
+
 		$this->classListNeedsRefresh = true;
 		if (!$name) { // builder is not ready for falsy names such as '0'
 			throw new Nette\InvalidArgumentException(sprintf('Service name must be a non-empty string, %s given.', gettype($name)));

tests/DI/ContainerBuilder.basic5.phpt

@@ -0,0 +1,22 @@
+<?php
+
+declare(strict_types=1);
+
+use Nette\DI;
+use Tester\Assert;
+
+
+require __DIR__ . '/../bootstrap.php';
+
+
+$builder = new DI\ContainerBuilder;
+$builder->addDefinition('1')
+	->setFactory('stdClass');
+$builder->addDefinition(null)
+	->setFactory('stdClass');
+
+
+$container = createContainer($builder);
+
+Assert::type(stdClass::class, $container->getService('1'));
+Assert::type(stdClass::class, $container->getService('2'));