bug symfony#17099 [Form] Fixed violation mapping if multiple forms are using the same (or part of the same) property path (alekitto)

This PR was squashed before being merged into the 2.3 branch (closes symfony#17099).

Discussion
----------

[Form] Fixed violation mapping if multiple forms are using the same (or part of the same) property path

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | symfony#5656
| License       | MIT
| Doc PR        |

Commits
-------

f005c80 [Form] Fixed violation mapping if multiple forms are using the same (or part of the same) property path

Author: fabpot

src/Symfony/Component/Form/Extension/Validator/ViolationMapper/ViolationMapper.php

@@ -147,12 +147,9 @@ public function mapViolation(ConstraintViolation $violation, FormInterface $form
      */
     private function matchChild(FormInterface $form, PropertyPathIteratorInterface $it)
     {
-        // Remember at what property path underneath "data"
-        // we are looking. Check if there is a child with that
-        // path, otherwise increase path by one more piece
+        $target = null;
         $chunk = '';
-        $foundChild = null;
-        $foundAtIndex = 0;
+        $foundAtIndex = null;
 
         // Construct mapping rules for the given form
         $rules = array();
@@ -164,17 +161,11 @@ private function matchChild(FormInterface $form, PropertyPathIteratorInterface $
             }
         }
 
-        // Skip forms inheriting their parent data when iterating the children
-        $childIterator = new \RecursiveIteratorIterator(
+        $children = iterator_to_array(new \RecursiveIteratorIterator(
             new InheritDataAwareIterator($form)
-        );
-
-        // Make the path longer until we find a matching child
-        while (true) {
-            if (!$it->valid()) {
-                return;
-            }
+        ));
 
+        while ($it->valid()) {
             if ($it->isIndex()) {
                 $chunk .= '['.$it->current().']';
             } else {
@@ -196,33 +187,27 @@ private function matchChild(FormInterface $form, PropertyPathIteratorInterface $
                 }
             }
 
-            // Test children unless we already found one
-            if (null === $foundChild) {
-                foreach ($childIterator as $child) {
-                    /* @var FormInterface $child */
-                    $childPath = (string) $child->getPropertyPath();
-
-                    // Child found, mark as return value
-                    if ($chunk === $childPath) {
-                        $foundChild = $child;
-                        $foundAtIndex = $it->key();
-                    }
+            /** @var FormInterface $child */
+            foreach ($children as $key => $child) {
+                $childPath = (string) $child->getPropertyPath();
+                if ($childPath === $chunk) {
+                    $target = $child;
+                    $foundAtIndex = $it->key();
+                } elseif (0 === strpos($childPath, $chunk)) {
+                    continue;
                 }
+
+                unset($children[$key]);
             }
 
-            // Add element to the chunk
             $it->next();
+        }
 
-            // If we reached the end of the path or if there are no
-            // more matching mapping rules, return the found child
-            if (null !== $foundChild && (!$it->valid() || count($rules) === 0)) {
-                // Reset index in case we tried to find mapping
-                // rules further down the path
-                $it->seek($foundAtIndex);
-
-                return $foundChild;
-            }
+        if (null !== $foundAtIndex) {
+            $it->seek($foundAtIndex);
         }
+
+        return $target;
     }
 
     /**

src/Symfony/Component/Form/Tests/Extension/Validator/ViolationMapper/ViolationMapperTest.php

@@ -1474,4 +1474,25 @@ public function testErrorMappingForFormInheritingParentData($target, $childName,
             $this->assertEquals(array($this->getFormError()), $grandChild->getErrors(), $grandChildName.' should have an error, but has none');
         }
     }
+
+    public function testBacktrackIfSeveralSubFormsWithSamePropertyPath()
+    {
+        $violation = $this->getConstraintViolation('data.address[street]');
+        $parent = $this->getForm('parent');
+        $child1 = $this->getForm('subform1', 'address');
+        $child2 = $this->getForm('subform2', 'address');
+        $grandChild = $this->getForm('street');
+
+        $parent->add($child1);
+        $parent->add($child2);
+        $child2->add($grandChild);
+
+        $this->mapper->mapViolation($violation, $parent);
+
+        // The error occurred on the child of the second form with the same path
+        $this->assertCount(0, $parent->getErrors(), $parent->getName().' should not have an error, but has one');
+        $this->assertCount(0, $child1->getErrors(), $child1->getName().' should not have an error, but has one');
+        $this->assertCount(0, $child2->getErrors(), $child2->getName().' should not have an error, but has one');
+        $this->assertEquals(array($this->getFormError()), $grandChild->getErrors(), $grandChild->getName().' should have an error, but has none');
+    }
 }