[Php80] Skip promoting a property the parent declares without a native type

[TomasVotruba]

Promoting a property that a parent declares without a native type produces code PHP refuses to load.

A child may redeclare an inherited untyped property, but it may not add a type to it. Promotion moves the parameter type onto the property, so it does exactly that:

abstract class ParentClass
{
    /**
     * @var SomeModel|null
     */
    protected $model;
}

final class ChildClass extends ParentClass
{
    /**
     * @var SomeModel|null
     */
    protected $model;

    public function __construct(SomeModel $model)
    {
        $this->model = $model;
    }
}

becomes

final class ChildClass extends ParentClass
{
    public function __construct(protected SomeModel $model)
    {
    }
}

which fatals on load:

PHP Fatal error: Type of ChildClass::$model must not be defined (as in class ParentClass)

This is not caught by the existing skips: the property is typed neither in the child nor via a conflicting docblock, so nothing signals the clash — the constraint lives entirely in the ancestor.

The fix

Skip promotion when the nearest ancestor declaring the property has no native type on it:

private function shouldSkipUntypedParentProperty(ClassReflection $classReflection, string $propertyName): bool
{
    foreach ($classReflection->getParents() as $parentClassReflection) {
        if (! $parentClassReflection->hasNativeProperty($propertyName)) {
            continue;
        }

        return ! $parentClassReflection->getNativeProperty($propertyName)
            ->hasNativeType();
    }

    return false;
}

It returns on the first ancestor that declares the property, since that is the declaration the child must stay compatible with. A parent property that is natively typed keeps promoting as before — the child simply has to repeat the same type, which promotion already does.

Test

skip_untyped_parent_property.php.inc with an UntypedPropertyParent source class. Verified it reproduces the bug: with the rule reverted the fixture fails —

Failed on fixture file "skip_untyped_parent_property.php.inc"
Tests: 56, Assertions: 58, Failures: 1

— and passes with the fix: OK (56 tests, 57 assertions).

Found while running Rector over a codebase where API controllers inherit an untyped protected $model from a shared base controller; every promoted child became unloadable.