[DI] Fix defaults overriding empty strings in AutowirePass

Author: nicolas-grekas

Compiler/AutowirePass.php

@@ -95,8 +95,10 @@ private function completeDefinition($id, Definition $definition)
                         throw new RuntimeException(sprintf('Unable to autowire argument index %d ($%s) for the service "%s". If this is an object, give it a type-hint. Otherwise, specify this argument\'s value explicitly.', $index, $parameter->name, $id));
                     }
 
-                    // specifically pass the default value
-                    $arguments[$index] = $parameter->getDefaultValue();
+                    if (!array_key_exists($index, $arguments)) {
+                        // specifically pass the default value
+                        $arguments[$index] = $parameter->getDefaultValue();
+                    }
 
                     continue;
                 }

Tests/Compiler/AutowirePassTest.php

@@ -443,6 +443,22 @@ public function testIgnoreServiceWithClassNotExisting()
 
         $this->assertTrue($container->hasDefinition('bar'));
     }
+
+    public function testEmptyStringIsKept()
+    {
+        $container = new ContainerBuilder();
+
+        $container->register('a', __NAMESPACE__.'\A');
+        $container->register('lille', __NAMESPACE__.'\Lille');
+        $container->register('foo', __NAMESPACE__.'\MultipleArgumentsOptionalScalar')
+            ->setAutowired(true)
+            ->setArguments(array('', ''));
+
+        $pass = new AutowirePass();
+        $pass->process($container);
+
+        $this->assertEquals(array(new Reference('a'), '', new Reference('lille')), $container->getDefinition('foo')->getArguments());
+    }
 }
 
 class Foo