Merge branch '3.4' into 4.1

* 3.4:
  [DI] dont fail on missing classes when resource tracking is disabled
  [Validator] Added the missing constraints instance checks

Author: nicolas-grekas

src/Symfony/Component/DependencyInjection/ContainerBuilder.php

@@ -348,7 +348,7 @@ public function getReflectionClass(?string $class, bool $throw = true): ?\Reflec
                 $resource = new ClassExistenceResource($class, false);
                 $classReflector = $resource->isFresh(0) ? false : new \ReflectionClass($class);
             } else {
-                $classReflector = new \ReflectionClass($class);
+                $classReflector = class_exists($class) ? new \ReflectionClass($class) : false;
             }
         } catch (\ReflectionException $e) {
             if ($throw) {

src/Symfony/Component/Validator/Constraints/BicValidator.php

@@ -13,6 +13,7 @@
 
 use Symfony\Component\Validator\Constraint;
 use Symfony\Component\Validator\ConstraintValidator;
+use Symfony\Component\Validator\Exception\UnexpectedTypeException;
 
 /**
  * @author Michael Hirschler <michael.vhirsch@gmail.com>
@@ -26,6 +27,10 @@ class BicValidator extends ConstraintValidator
      */
     public function validate($value, Constraint $constraint)
     {
+        if (!$constraint instanceof Bic) {
+            throw new UnexpectedTypeException($constraint, __NAMESPACE__.'\Bic');
+        }
+
         if (null === $value || '' === $value) {
             return;
         }

src/Symfony/Component/Validator/Constraints/CountValidator.php

@@ -25,6 +25,10 @@ class CountValidator extends ConstraintValidator
      */
     public function validate($value, Constraint $constraint)
     {
+        if (!$constraint instanceof Count) {
+            throw new UnexpectedTypeException($constraint, __NAMESPACE__.'\Count');
+        }
+
         if (null === $value) {
             return;
         }

src/Symfony/Component/Validator/Constraints/UuidValidator.php

@@ -66,14 +66,14 @@ class UuidValidator extends ConstraintValidator
      */
     public function validate($value, Constraint $constraint)
     {
-        if (null === $value || '' === $value) {
-            return;
-        }
-
         if (!$constraint instanceof Uuid) {
             throw new UnexpectedTypeException($constraint, __NAMESPACE__.'\Uuid');
         }
 
+        if (null === $value || '' === $value) {
+            return;
+        }
+
         if (!is_scalar($value) && !(\is_object($value) && method_exists($value, '__toString'))) {
             throw new UnexpectedTypeException($value, 'string');
         }