bug #32541 [HttpKernel] trim the leading backslash in the controller …

…init (Simperfit, fabpot)

This PR was submitted for the 4.4 branch but it was merged into the 4.3 branch instead (closes #32541).

Discussion
----------

[HttpKernel] trim the leading backslash in the controller init

| Q             | A
| ------------- | ---
| Branch?       | 4.4
| Bug fix?      | no
| New feature?  | no <!-- please update src/**/CHANGELOG.md files -->
| BC breaks?    | no     <!-- see https://symfony.com/bc -->
| Deprecations? | no <!-- please update UPGRADE-*.md and src/**/CHANGELOG.md files -->
| Tests pass?   | yes    <!-- please add some, will be required by reviewers -->
| Fixed tickets | #29945
| License       | MIT
| Doc PR        | none <!-- required for new features -->

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This fixes an error where the classes exists when using a leading backslash in the controller, it's not invalid to do so.

see #30045 (comment)

Commits
-------

3c8d395 [HttpKernel] fixed class having a leading \ in a route controller
6fdf252 [HttpKernel] trim the leading backslash in the controller init

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

@@ -47,6 +47,8 @@ protected function createController($controller)
      */
     protected function instantiateController($class)
     {
+        $class = ltrim($class, '\\');
+
         if ($this->container->has($class)) {
             return $this->container->get($class);
         }

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

@@ -119,6 +119,36 @@ public function testGetControllerInvokableServiceWithClassNameAsName()
         $this->assertSame($service, $controller);
     }
 
+    /**
+     * @dataProvider getControllers
+     */
+    public function testInstantiateControllerWhenControllerStartsWithABackslash($controller)
+    {
+        $service = new ControllerTestService('foo');
+        $class = ControllerTestService::class;
+
+        $container = $this->createMockContainer();
+        $container->expects($this->once())->method('has')->with($class)->willReturn(true);
+        $container->expects($this->once())->method('get')->with($class)->willReturn($service);
+
+        $resolver = $this->createControllerResolver(null, $container);
+        $request = Request::create('/');
+        $request->attributes->set('_controller', $controller);
+
+        $controller = $resolver->getController($request);
+
+        $this->assertInstanceOf(ControllerTestService::class, $controller[0]);
+        $this->assertSame('action', $controller[1]);
+    }
+
+    public function getControllers()
+    {
+        return [
+            ['\\'.ControllerTestService::class.'::action'],
+            ['\\'.ControllerTestService::class.':action'],
+        ];
+    }
+
     public function testExceptionWhenUsingRemovedControllerServiceWithClassNameAsName()
     {
         $this->expectException('InvalidArgumentException');