[Validator] Fix fields without constraints in Collection

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

@@ -42,7 +42,7 @@ class Collection extends Composite
      */
     public function __construct($fields = null, ?array $groups = null, $payload = null, ?bool $allowExtraFields = null, ?bool $allowMissingFields = null, ?string $extraFieldsMessage = null, ?string $missingFieldsMessage = null)
     {
-        if (\is_array($fields) && ([] === $fields || ($firstField = reset($fields)) instanceof Constraint || ($firstField[0] ?? null) instanceof Constraint)) {
+        if (self::isFieldsOption($fields)) {
             $fields = ['fields' => $fields];
         }
 
@@ -87,4 +87,31 @@ protected function getCompositeOption()
     {
         return 'fields';
     }
+
+    private static function isFieldsOption($options): bool
+    {
+        if (!\is_array($options)) {
+            return false;
+        }
+
+        foreach ($options as $optionOrField) {
+            if ($optionOrField instanceof Constraint) {
+                return true;
+            }
+
+            if (null === $optionOrField) {
+                continue;
+            }
+
+            if (!\is_array($optionOrField)) {
+                return false;
+            }
+
+            if ($optionOrField && !($optionOrField[0] ?? null) instanceof Constraint) {
+                return false;
+            }
+        }
+
+        return true;
+    }
 }

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

@@ -170,6 +170,50 @@ public function testEmptyFieldsInOptions()
             'extraFieldsMessage' => 'foo bar baz',
         ]);
 
+        $this->assertSame([], $constraint->fields);
+        $this->assertTrue($constraint->allowExtraFields);
+        $this->assertSame('foo bar baz', $constraint->extraFieldsMessage);
+    }
+
+    /**
+     * @testWith [[]]
+     *           [null]
+     */
+    public function testEmptyConstraintListForField(?array $fieldConstraint)
+    {
+        $constraint = new Collection(
+            [
+                'foo' => $fieldConstraint,
+            ],
+            null,
+            null,
+            true,
+            null,
+            'foo bar baz'
+        );
+
+        $this->assertArrayHasKey('foo', $constraint->fields);
+        $this->assertInstanceOf(Required::class, $constraint->fields['foo']);
+        $this->assertTrue($constraint->allowExtraFields);
+        $this->assertSame('foo bar baz', $constraint->extraFieldsMessage);
+    }
+
+    /**
+     * @testWith [[]]
+     *           [null]
+     */
+    public function testEmptyConstraintListForFieldInOptions(?array $fieldConstraint)
+    {
+        $constraint = new Collection([
+            'fields' => [
+                'foo' => $fieldConstraint,
+            ],
+            'allowExtraFields' => true,
+            'extraFieldsMessage' => 'foo bar baz',
+        ]);
+
+        $this->assertArrayHasKey('foo', $constraint->fields);
+        $this->assertInstanceOf(Required::class, $constraint->fields['foo']);
         $this->assertTrue($constraint->allowExtraFields);
         $this->assertSame('foo bar baz', $constraint->extraFieldsMessage);
     }