Merge branch '3.4' into 4.3

* 3.4:
  Fix inconsistent return points.
  Fix remaining tests

Author: nicolas-grekas

Compiler/AutowirePass.php

@@ -309,6 +309,8 @@ private function getAutowiredReference(TypedReference $reference)
         if ($this->container->has($type) && !$this->container->findDefinition($type)->isAbstract()) {
             return new TypedReference($type, $type, $reference->getInvalidBehavior());
         }
+
+        return null;
     }
 
     /**
@@ -441,7 +443,7 @@ private function createTypeAlternatives(ContainerBuilder $container, TypedRefere
         } elseif (isset($this->types[$type])) {
             $message = sprintf('the existing "%s" service', $this->types[$type]);
         } else {
-            return;
+            return '';
         }
 
         return sprintf(' You should maybe alias this %s to %s.', class_exists($type, false) ? 'class' : 'interface', $message);
@@ -470,5 +472,7 @@ private function getAliasesSuggestionForType(ContainerBuilder $container, $type,
         if ($aliases) {
             return sprintf('Try changing the type-hint%s to "%s" instead.', $extraContext, $aliases[0]);
         }
+
+        return null;
     }
 }

Loader/XmlFileLoader.php

@@ -230,7 +230,7 @@ private function parseDefinition(\DOMElement $service, $file, array $defaults)
                 $alias->setDeprecated(true, $deprecated[0]->nodeValue ?: null);
             }
 
-            return;
+            return null;
         }
 
         if ($this->isLoadingInstanceof) {