bug #22396 Prevent double registrations related to tag priorities (nicolas-grekas)

This PR was merged into the 2.7 branch.

Discussion
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Prevent double registrations related to tag priorities

| Q             | A
| ------------- | ---
| Branch?       | 2.7
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | -
| License       | MIT
| Doc PR        | -

The current logic is inconsistent, and allows the same id to be used several times. This makes the first explicit priority to always win.

Commits
-------

6764dcdf39 Prevent double registrations related to tag priorities

Author: fabpot

DependencyInjection/Compiler/SerializerPass.php

@@ -47,11 +47,9 @@ private function findAndSortTaggedServices($tagName, ContainerBuilder $container
         }
 
         $sortedServices = array();
-        foreach ($services as $serviceId => $tags) {
-            foreach ($tags as $tag) {
-                $priority = isset($tag['priority']) ? $tag['priority'] : 0;
-                $sortedServices[$priority][] = new Reference($serviceId);
-            }
+        foreach ($services as $serviceId => $attributes) {
+            $priority = isset($attributes[0]['priority']) ? $attributes[0]['priority'] : 0;
+            $sortedServices[$priority][] = new Reference($serviceId);
         }
 
         krsort($sortedServices);

Tests/DependencyInjection/Compiler/SerializerPassTest.php

@@ -72,9 +72,9 @@ public function testThrowExceptionWhenNoEncoders()
     public function testServicesAreOrderedAccordingToPriority()
     {
         $services = array(
-            'n3' => array('tag' => array()),
-            'n1' => array('tag' => array('priority' => 200)),
-            'n2' => array('tag' => array('priority' => 100)),
+            'n3' => array(array()),
+            'n1' => array(array('priority' => 200)),
+            'n2' => array(array('priority' => 100)),
         );
 
         $expected = array(