bug #18759 [Validator] Support for DateTimeImmutable (krzysiekpiasecki)

This PR was squashed before being merged into the 3.0 branch (closes #18759).

Discussion
----------

[Validator] Support for DateTimeImmutable

| Q             | A
| ------------- | ---
| Branch?       | 3.0
| Bug fix?      | no
| New feature?  | yes
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | #18752
| License       | MIT
| Doc PR        |

When validating with DateTime constraint UnexpectedTypeException is thrown for DateTimeImmutable instances.

Why PR?
- DateTimeImmutable behaves like a DateTime. Both implements the same interface DateTimeInterface.
- DateTimeInterface cannot be implemented by the client.

Commits
-------

f49659f [Validator] Support for DateTimeImmutable

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

@@ -30,7 +30,7 @@ class DateTimeValidator extends DateValidator
             throw new UnexpectedTypeException($constraint, __NAMESPACE__.'\DateTime');
         }
 
-        if (null === $value || '' === $value || $value instanceof \DateTime) {
+        if (null === $value || '' === $value || $value instanceof \DateTimeInterface) {
             return;
         }
 

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

@@ -47,7 +47,7 @@ class DateValidator extends ConstraintValidator
             throw new UnexpectedTypeException($constraint, __NAMESPACE__.'\Date');
         }
 
-        if (null === $value || '' === $value || $value instanceof \DateTime) {
+        if (null === $value || '' === $value || $value instanceof \DateTimeInterface) {
             return;
         }
 

src/Symfony/Component/Validator/Tests/Constraints/DateTimeValidatorTest.php

@@ -42,6 +42,13 @@ class DateTimeValidatorTest extends AbstractConstraintValidatorTest
         $this->assertNoViolation();
     }
 
+    public function testDateTimeImmutableClassIsValid()
+    {
+        $this->validator->validate(new \DateTimeImmutable(), new DateTime());
+
+        $this->assertNoViolation();
+    }
+
     /**
      * @expectedException \Symfony\Component\Validator\Exception\UnexpectedTypeException
      */

src/Symfony/Component/Validator/Tests/Constraints/DateValidatorTest.php

@@ -42,6 +42,13 @@ class DateValidatorTest extends AbstractConstraintValidatorTest
         $this->assertNoViolation();
     }
 
+    public function testDateTimeImmutableClassIsValid()
+    {
+        $this->validator->validate(new \DateTimeImmutable(), new Date());
+
+        $this->assertNoViolation();
+    }
+
     /**
      * @expectedException \Symfony\Component\Validator\Exception\UnexpectedTypeException
      */