Merge branch '3.1'

* 3.1:
  [travis/appveyor] Wire simple-phpunit
  [Console] fixed PHP7 Errors are now handled and converted to Exceptions
  Fix #19721
  Fix translation:update command count
  bumped Symfony version to 2.8.12
  updated VERSION for 2.8.11
  updated CHANGELOG for 2.8.11
  bumped Symfony version to 2.7.19
  updated VERSION for 2.7.18
  update CONTRIBUTORS for 2.7.18
  updated CHANGELOG for 2.7.18
  [Security] Optimize RoleHierarchy's buildRoleMap method
  [FrameworkBundle] Fix Incorrect line break in exception message (500 debug page)
  [Security] Added note inside phpdoc.
  Minor cleanups and improvements
  [form] lazy trans `post_max_size_message`.
  [DI] Fix setting synthetic services on ContainerBuilder
  [ClassLoader] Fix ClassCollectionLoader inlining with declare(strict_types=1)

Author: nicolas-grekas

Core/Authorization/Voter/Voter.php

@@ -58,6 +58,7 @@ abstract protected function supports($attribute, $subject);
 
     /**
      * Perform a single access check operation on a given attribute, subject and token.
+     * It is safe to assume that $attribute and $subject already passed the "supports()" method check.
      *
      * @param string         $attribute
      * @param mixed          $subject

Core/Role/RoleHierarchy.php

@@ -65,9 +65,17 @@ protected function buildRoleMap()
                 }
 
                 $visited[] = $role;
-                $this->map[$main] = array_unique(array_merge($this->map[$main], $this->hierarchy[$role]));
-                $additionalRoles = array_merge($additionalRoles, array_diff($this->hierarchy[$role], $visited));
+
+                foreach ($this->hierarchy[$role] as $roleToAdd) {
+                    $this->map[$main][] = $roleToAdd;
+                }
+
+                foreach (array_diff($this->hierarchy[$role], $visited) as $additionalRole) {
+                    $additionalRoles[] = $additionalRole;
+                }
             }
+
+            $this->map[$main] = array_unique($this->map[$main]);
         }
     }
 }