bug #19811 Fixed the nullable support for php 7.1 and below (2.7, 2.8, 3.0) (iltar)

This PR was merged into the 2.7 branch.

Discussion
----------

Fixed the nullable support for php 7.1 and below (2.7, 2.8, 3.0)

| Q             | A
| ------------- | ---
| Branch?       | 2.7, 2.8, 3.0
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | https://github.com/symfony/symfony/pull/19784#issuecomment-243852825
| License       | MIT
| Doc PR        | ~

Fixes the nullable support for 2.7, 2.8 and 3.0, can probably be partially merged into 3.1 but not 100% sure.

/ping @fabpot

Commits
-------

9c48756 Fixed the nullable support for php 7.1 and below

src/Symfony/Component/HttpKernel/Controller/ControllerResolver.php

@@ -27,6 +27,15 @@ class ControllerResolver implements ControllerResolverInterface
 {
     private $logger;
 
+    /**
+     * If the ...$arg functionality is available.
+     *
+     * Requires at least PHP 5.6.0 or HHVM 3.9.1
+     *
+     * @var bool
+     */
+    private $supportsVariadic;
+
     /**
      * Constructor.
      *
@@ -35,6 +44,8 @@ class ControllerResolver implements ControllerResolverInterface
     public function __construct(LoggerInterface $logger = null)
     {
         $this->logger = $logger;
+
+        $this->supportsVariadic = method_exists('ReflectionParameter', 'isVariadic');
     }
 
     /**
@@ -99,13 +110,20 @@ class ControllerResolver implements ControllerResolverInterface
         return $this->doGetArguments($request, $controller, $r->getParameters());
     }
 
+    /**
+     * @param Request                $request
+     * @param callable               $controller
+     * @param \ReflectionParameter[] $parameters
+     *
+     * @return array The arguments to use when calling the action
+     */
     protected function doGetArguments(Request $request, $controller, array $parameters)
     {
         $attributes = $request->attributes->all();
         $arguments = array();
         foreach ($parameters as $param) {
             if (array_key_exists($param->name, $attributes)) {
-                if (PHP_VERSION_ID >= 50600 && $param->isVariadic() && is_array($attributes[$param->name])) {
+                if ($this->supportsVariadic && $param->isVariadic() && is_array($attributes[$param->name])) {
                     $arguments = array_merge($arguments, array_values($attributes[$param->name]));
                 } else {
                     $arguments[] = $attributes[$param->name];
@@ -114,6 +132,8 @@ class ControllerResolver implements ControllerResolverInterface
                 $arguments[] = $request;
             } elseif ($param->isDefaultValueAvailable()) {
                 $arguments[] = $param->getDefaultValue();
+            } elseif ($param->allowsNull()) {
+                $arguments[] = null;
             } else {
                 if (is_array($controller)) {
                     $repr = sprintf('%s::%s()', get_class($controller[0]), $controller[1]);

src/Symfony/Component/HttpKernel/Tests/Controller/ControllerResolverTest.php

@@ -13,6 +13,7 @@ namespace Symfony\Component\HttpKernel\Tests\Controller;
 
 use Psr\Log\LoggerInterface;
 use Symfony\Component\HttpKernel\Controller\ControllerResolver;
+use Symfony\Component\HttpKernel\Tests\Fixtures\Controller\NullableController;
 use Symfony\Component\HttpKernel\Tests\Fixtures\Controller\VariadicController;
 use Symfony\Component\HttpFoundation\Request;
 
@@ -222,6 +223,34 @@ class ControllerResolverTest extends \PHPUnit_Framework_TestCase
         $mock->getController($request);
     }
 
+    /**
+     * @requires PHP 7.1
+     */
+    public function testGetNullableArguments()
+    {
+        $resolver = new ControllerResolver();
+
+        $request = Request::create('/');
+        $request->attributes->set('foo', 'foo');
+        $request->attributes->set('bar', new \stdClass());
+        $request->attributes->set('mandatory', 'mandatory');
+        $controller = array(new NullableController(), 'action');
+        $this->assertEquals(array('foo', new \stdClass(), 'value', 'mandatory'), $resolver->getArguments($request, $controller));
+    }
+
+    /**
+     * @requires PHP 7.1
+     */
+    public function testGetNullableArgumentsWithDefaults()
+    {
+        $resolver = new ControllerResolver();
+
+        $request = Request::create('/');
+        $request->attributes->set('mandatory', 'mandatory');
+        $controller = array(new NullableController(), 'action');
+        $this->assertEquals(array(null, null, 'value', 'mandatory'), $resolver->getArguments($request, $controller));
+    }
+
     protected function createControllerResolver(LoggerInterface $logger = null)
     {
         return new ControllerResolver($logger);

src/Symfony/Component/HttpKernel/Tests/Fixtures/Controller/NullableController.php

@@ -0,0 +1,19 @@
+<?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\HttpKernel\Tests\Fixtures\Controller;
+
+class NullableController
+{
+    public function action(?string $foo, ?\stdClass $bar, ?string $baz = 'value', $mandatory)
+    {
+    }
+}