Merge branch '2.8' into 3.1

* 2.8:
  [Routing] Fail properly when a route parameter name cannot be used as a PCRE subpattern name
  [FrameworkBundle] Improve performance of ControllerNameParser
  Update documentation link to the component
  [HttpFoundation] Add links to RFC-7231
  [DI] Initialize properties before method calls
  Tag missing internals
  [WebProfilerBundle] Dont use request attributes in RouterController
  Fix complete config tests

Author: nicolas-grekas

Controller/ControllerNameParser.php

@@ -46,11 +46,12 @@ public function __construct(KernelInterface $kernel)
      */
     public function parse($controller)
     {
-        $originalController = $controller;
-        if (3 !== count($parts = explode(':', $controller))) {
+        $parts = explode(':', $controller);
+        if (3 !== count($parts) || in_array('', $parts, true)) {
             throw new \InvalidArgumentException(sprintf('The "%s" controller is not a valid "a:b:c" controller string.', $controller));
         }
 
+        $originalController = $controller;
         list($bundle, $controller, $action) = $parts;
         $controller = str_replace('/', '\\', $controller);
         $bundles = array();

Routing/DelegatingLoader.php

@@ -20,7 +20,7 @@
  * DelegatingLoader delegates route loading to other loaders using a loader resolver.
  *
  * This implementation resolves the _controller attribute from the short notation
- * to the fully-qualified form (from a:b:c to class:method).
+ * to the fully-qualified form (from a:b:c to class::method).
  *
  * @author Fabien Potencier <fabien@symfony.com>
  */
@@ -75,15 +75,17 @@ public function load($resource, $type = null)
         }
 
         foreach ($collection->all() as $route) {
-            if ($controller = $route->getDefault('_controller')) {
-                try {
-                    $controller = $this->parser->parse($controller);
-                } catch (\InvalidArgumentException $e) {
-                    // unable to optimize unknown notation
-                }
+            if (!$controller = $route->getDefault('_controller')) {
+                continue;
+            }
 
-                $route->setDefault('_controller', $controller);
+            try {
+                $controller = $this->parser->parse($controller);
+            } catch (\InvalidArgumentException $e) {
+                // unable to optimize unknown notation
             }
+
+            $route->setDefault('_controller', $controller);
         }
 
         return $collection;