minor symfony#24599 Tweaking class not found autowiring error (weaverryan)

This PR was squashed before being merged into the 3.3 branch (closes symfony#24599).

Discussion
----------

Tweaking class not found autowiring error

| Q             | A
| ------------- | ---
| Branch?       | 3.3
| Bug fix?      | no
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | none
| License       | MIT
| Doc PR        | n/a

A trainee in my workshop today hit this error, and it struck me as not as clear as it could be - it's really a "Class Not Found" error.

Commits
-------

48832e6 Tweaking class not found autowiring error

Author: fabpot

src/Symfony/Component/DependencyInjection/Compiler/AutowirePass.php

@@ -11,6 +11,7 @@
 
 namespace Symfony\Component\DependencyInjection\Compiler;
 
+use Symfony\Component\Config\Resource\ClassExistenceResource;
 use Symfony\Component\DependencyInjection\Config\AutowireServiceResource;
 use Symfony\Component\DependencyInjection\ContainerBuilder;
 use Symfony\Component\DependencyInjection\Definition;
@@ -485,7 +486,17 @@ private function createAutowiredDefinition($type)
     private function createTypeNotFoundMessage(TypedReference $reference, $label)
     {
         if (!$r = $this->container->getReflectionClass($type = $reference->getType(), false)) {
-            $message = sprintf('has type "%s" but this class cannot be loaded.', $type);
+            // either $type does not exist or a parent class does not exist
+            try {
+                $resource = new ClassExistenceResource($type, false);
+                // isFresh() will explode ONLY if a parent class/trait does not exist
+                $resource->isFresh(0);
+                $parentMsg = false;
+            } catch (\ReflectionException $e) {
+                $parentMsg = $e->getMessage();
+            }
+
+            $message = sprintf('has type "%s" but this class %s.', $type, $parentMsg ? sprintf('is missing a parent class (%s)', $parentMsg) : 'was not found');
         } else {
             $message = $this->container->has($type) ? 'this service is abstract' : 'no such service exists';
             $message = sprintf('references %s "%s" but %s.%s', $r->isInterface() ? 'interface' : 'class', $type, $message, $this->createTypeAlternatives($reference));

src/Symfony/Component/DependencyInjection/Tests/Compiler/AutowirePassTest.php

@@ -359,7 +359,7 @@ public function testDontTriggerAutowiring()
 
     /**
      * @expectedException \Symfony\Component\DependencyInjection\Exception\AutowiringFailedException
-     * @expectedExceptionMessage Cannot autowire service "a": argument "$r" of method "Symfony\Component\DependencyInjection\Tests\Compiler\BadTypeHintedArgument::__construct()" has type "Symfony\Component\DependencyInjection\Tests\Compiler\NotARealClass" but this class cannot be loaded.
+     * @expectedExceptionMessage Cannot autowire service "a": argument "$r" of method "Symfony\Component\DependencyInjection\Tests\Compiler\BadTypeHintedArgument::__construct()" has type "Symfony\Component\DependencyInjection\Tests\Compiler\NotARealClass" but this class was not found.
      */
     public function testClassNotFoundThrowsException()
     {
@@ -374,7 +374,7 @@ public function testClassNotFoundThrowsException()
 
     /**
      * @expectedException \Symfony\Component\DependencyInjection\Exception\AutowiringFailedException
-     * @expectedExceptionMessage Cannot autowire service "a": argument "$r" of method "Symfony\Component\DependencyInjection\Tests\Compiler\BadParentTypeHintedArgument::__construct()" has type "Symfony\Component\DependencyInjection\Tests\Compiler\OptionalServiceClass" but this class cannot be loaded.
+     * @expectedExceptionMessage Cannot autowire service "a": argument "$r" of method "Symfony\Component\DependencyInjection\Tests\Compiler\BadParentTypeHintedArgument::__construct()" has type "Symfony\Component\DependencyInjection\Tests\Compiler\OptionalServiceClass" but this class is missing a parent class (Class Symfony\Bug\NotExistClass not found).
      */
     public function testParentClassNotFoundThrowsException()
     {
@@ -761,7 +761,7 @@ public function testNotWireableCalls($method, $expectedMsg)
     public function provideNotWireableCalls()
     {
         return array(
-            array('setNotAutowireable', 'Cannot autowire service "foo": argument "$n" of method "Symfony\Component\DependencyInjection\Tests\Compiler\NotWireable::setNotAutowireable()" has type "Symfony\Component\DependencyInjection\Tests\Compiler\NotARealClass" but this class cannot be loaded.'),
+            array('setNotAutowireable', 'Cannot autowire service "foo": argument "$n" of method "Symfony\Component\DependencyInjection\Tests\Compiler\NotWireable::setNotAutowireable()" has type "Symfony\Component\DependencyInjection\Tests\Compiler\NotARealClass" but this class was not found.'),
             array('setDifferentNamespace', 'Cannot autowire service "foo": argument "$n" of method "Symfony\Component\DependencyInjection\Tests\Compiler\NotWireable::setDifferentNamespace()" references class "stdClass" but no such service exists. It cannot be auto-registered because it is from a different root namespace.'),
             array(null, 'Cannot autowire service "foo": method "Symfony\Component\DependencyInjection\Tests\Compiler\NotWireable::setProtectedMethod()" must be public.'),
         );

src/Symfony/Component/DependencyInjection/composer.json

@@ -32,7 +32,7 @@
         "symfony/proxy-manager-bridge": "Generate service proxies to lazy load them"
     },
     "conflict": {
-        "symfony/config": "<3.3.1",
+        "symfony/config": "<3.3.7",
         "symfony/finder": "<3.3",
         "symfony/yaml": "<3.3"
     },