Symfony version(s) affected

7.3

Description

Description

The Length or Count constraint in XML configuration has a backward compatibility break when using the value instead of exactly option in Symfony 7.3+.

When using named parameters with #[HasNamedArguments] in the Length constraint constructor, the XML loader attempts to pass the value option as a named parameter.

Since $value is not a constructor argument, this results in an "Unknown named parameter $value" error.

How to reproduce

Legacy XML configuration (Symfony 7.2):

<constraint name="Length">
    <option name="value">6</option>
    <option name="group">Foo</option>
</constraint>

Current XML configuration (Symfony 7.3+):

<constraint name="Length">
    <option name="exactly">6</option>
    <option name="group">Foo</option>
</constraint>

Possible Solution

The AbstractLoader now automatically maps the value option to exactly for the Length or Count constraint.
This ensures backward compatibility with legacy XML configuration while triggering a deprecation notice.

A more abstract solution would be to inspect the constructor of the constraint using reflection.
If the constructor has an $exactly parameter but no $value parameter, the loader can automatically map the passed value option to exactly:

$constructor = new \ReflectionMethod($className, '__construct');
$params = array_map(fn($p) => $p->getName(), $constructor->getParameters());

if (isset($options['value']) && in_array('exactly', $params, true) && !in_array('value', $params, true)) {
    $options['exactly'] = $options['value'];
    unset($options['value']);
}

Additional Context

Additionally, the current condition only applies when the XML config provides more than one option.