bug #21053 [Validator] override property constraints in child class (xabbuh)

This PR was merged into the 2.7 branch.

Discussion
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[Validator] override property constraints in child class

| Q             | A
| ------------- | ---
| Branch?       | 2.7
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | #15950
| License       | MIT
| Doc PR        |

Commits
-------

8b281fe override property constraints in child class

Author: fabpot

src/Symfony/Component/Validator/Mapping/ClassMetadata.php

@@ -346,6 +346,10 @@ public function mergeConstraints(ClassMetadata $source)
         }
 
         foreach ($source->getConstrainedProperties() as $property) {
+            if ($this->hasPropertyMetadata($property)) {
+                continue;
+            }
+
             foreach ($source->getPropertyMetadata($property) as $member) {
                 $member = clone $member;
 

src/Symfony/Component/Validator/Tests/Mapping/ClassMetadataTest.php

@@ -12,6 +12,7 @@
 namespace Symfony\Component\Validator\Tests\Mapping;
 
 use Symfony\Component\Validator\Constraint;
+use Symfony\Component\Validator\Constraints\GreaterThan;
 use Symfony\Component\Validator\Constraints\Valid;
 use Symfony\Component\Validator\Mapping\ClassMetadata;
 use Symfony\Component\Validator\Tests\Fixtures\ConstraintA;
@@ -295,4 +296,29 @@ public function testGetPropertyMetadataReturnsEmptyArrayWithoutConfiguredMetadat
     {
         $this->assertCount(0, $this->metadata->getPropertyMetadata('foo'), '->getPropertyMetadata() returns an empty collection if no metadata is configured for the given property');
     }
+
+    public function testMergeDoesOverrideConstraintsFromParentClassIfPropertyIsOverriddenInChildClass()
+    {
+        $parentMetadata = new ClassMetadata('\Symfony\Component\Validator\Tests\Mapping\ParentClass');
+        $parentMetadata->addPropertyConstraint('example', new GreaterThan(0));
+
+        $childMetadata = new ClassMetadata('\Symfony\Component\Validator\Tests\Mapping\ChildClass');
+        $childMetadata->addPropertyConstraint('example', new GreaterThan(1));
+        $childMetadata->mergeConstraints($parentMetadata);
+
+        $expectedMetadata = new ClassMetadata('\Symfony\Component\Validator\Tests\Mapping\ChildClass');
+        $expectedMetadata->addPropertyConstraint('example', new GreaterThan(1));
+
+        $this->assertEquals($expectedMetadata, $childMetadata);
+    }
+}
+
+class ParentClass
+{
+    public $example = 0;
+}
+
+class ChildClass extends ParentClass
+{
+    public $example = 1;    // overrides parent property of same name
 }