NelmioApiDocBundle/ModelDescriber/EnumModelDescriber.php

<?php

namespace Nelmio\ApiDocBundle\ModelDescriber;

use Nelmio\ApiDocBundle\Model\Model;
use OpenApi\Annotations\Schema;
use Symfony\Component\PropertyInfo\Type;

class EnumModelDescriber implements ModelDescriberInterface
{
    public function describe(Model $model, Schema $schema)
    {
        $enumClass = $model->getType()->getClassName();

        $enums = [];
        foreach ($enumClass::cases() as $enumCase) {
            $enums[] = $enumCase->value;
        }

        $schema->type = is_subclass_of($enumClass, \IntBackedEnum::class) ? 'int' : 'string';
        $schema->enum = $enums;
    }

    public function supports(Model $model): bool
    {
        if (!function_exists('enum_exists')) {
            return false;
        }

        return Type::BUILTIN_TYPE_OBJECT === $model->getType()->getBuiltinType()
            && enum_exists($model->getType()->getClassName())
            && is_subclass_of($model->getType()->getClassName(), \BackedEnum::class);
    }
}