bug #44854 [Validator] throw when Constraint::_construct() has not be…

…en called (nicolas-grekas)

This PR was merged into the 4.4 branch.

Discussion
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[Validator] throw when Constraint::_construct() has not been called

| Q             | A
| ------------- | ---
| Branch?       | 4.4
| Bug fix?      | yes
| New feature?  | no
| Deprecations? | no
| Tickets       | Fix #44846
| License       | MIT
| Doc PR        | -

Instead of #44847

Commits
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20aacce [Validator] throw when Constraint::_construct() has not been called

src/Symfony/Component/Validator/Constraint.php

@@ -226,6 +226,10 @@ public function __isset($option)
      */
     public function addImplicitGroupName($group)
     {
+        if (null === $this->groups && \array_key_exists('groups', (array) $this)) {
+            throw new \LogicException(sprintf('"%s::$groups" is set to null. Did you forget to call "%s::__construct()"?', static::class, self::class));
+        }
+
         if (\in_array(self::DEFAULT_GROUP, $this->groups) && !\in_array($group, $this->groups)) {
             $this->groups[] = $group;
         }