## Problem/Motivation Under Drupal 12, Symfony 8 declares the base validator as: ```php public function validate(mixed $value, Constraint $constraint): void; ``` Six constraint validators in this project still declare `validate()` with no return type. A missing return type is wider than `void`, so PHP rejects the override with a fatal error at class load time: ``` PHP Fatal error: Declaration of Drupal\ai\Plugin\Validation\Constraint\SimpleToolItemsConstraintValidator::validate($value, Symfony\Component\Validator\Constraint $constraint) must be compatible with Symfony\Component\Validator\ConstraintValidator::validate(mixed $value, Symfony\Component\Validator\Constraint $constraint): void in .../ai/src/Plugin/Validation/Constraint/SimpleToolItemsConstraintValidator.php on line 23 ``` The fatal is raised during plugin discovery (`AttributeClassDiscovery::getDefinitions()` calling `class_exists()`), so it takes down anything that builds a typed-config constraint. That includes every kernel test in a dependent project. Found while running the `ai_integration_eca` "next major" pipeline against Drupal 12 with `ai` 1.4.6, where it produced 141 identical fatals and made a Drupal 12 test run impossible: https://git.drupalcode.org/project/ai_integration_eca/-/merge_requests/13 ## Affected files | File | Line | |------|------| | `src/Plugin/Validation/Constraint/FixedValueValidator.php` | 19 | | `src/Plugin/Validation/Constraint/SimpleToolItemsConstraintValidator.php` | 23 | | `src/Plugin/Validation/Constraint/ComplexToolItemsConstraintValidator.php` | 47 | | `modules/ai_validations/src/Plugin/Validation/Constraint/AiImageClassificationConstraintValidator.php` | 59 | | `modules/ai_validations/src/Plugin/Validation/Constraint/AiImageConstraintValidator.php` | 60 | | `modules/ai_validations/src/Plugin/Validation/Constraint/AiTextConstraintValidator.php` | 47 | Fixing only one of them moves the fatal to the next validator in discovery order, so all six need to change together. Four sibling validators already declare `: void` (`ProviderModelDependencyConstraintValidator`, `AiJsonSchemaConstraintValidator`, `ValidStructuredOutputSchemaValidator`, `ValidJsonSchemaStructureValidator`), so this is an incompletely applied convention rather than a new one. ## Proposed resolution Add the `: void` return type to the six `validate()` methods. This is backward compatible. Symfony 6 and 7 declare `validate()` with no return type, and narrowing a return type in a child class is allowed, so the change is safe on Drupal 10 and 11 as well. There is no behavior change: none of the six methods returns a value. The untyped `$value` parameter is deliberately left alone. Parameter types are contravariant in PHP and an untyped parameter already accepts `mixed`, so it is not part of the incompatibility. `AiJsonSchemaConstraintValidator` declares exactly `validate($value, Constraint $constraint): void` and does not fatal under Drupal 12, which confirms the return type is the only problem. ## Remaining tasks - [ ] Add `: void` to the six `validate()` methods - [ ] Port to 1.5.x, 2.0.x and 1.x, which are all affected ## User interface changes None. ## API changes None. ## Data model changes None.