Cannot autowire service: Argument references class but no such service exists

Question

I'm upgrading a project from Symfony 3 to Symfony 4 (https://github.com/symfony/symfony/blob/master/UPGRADE-4.0.md) and I have many repository/services like this:

namespace App\Entity;

use App\Entity\Activation;
use Doctrine\ORM\EntityRepository;
use Predis\Client;

class ActivationRepository extends EntityRepository
{
    // ...
}

And when I try to run the project in the browser like this:

http://localhost:8000/login

I get this error:

(1/1) RuntimeException
Cannot autowire service "App\Entity\ActivationRepository": 
argument "$class" of method 
"Doctrine\ORM\EntityRepository::__construct()" 
references class "Doctrine\ORM\Mapping\ClassMetadata" 
but no such service exists.

Does this mean you have to create a service for "Doctrine\ORM\Mapping\ClassMetadata" in your services.yaml file?

Thanks to autowiring my new services.yaml file is fairly small compared to the old one, which had 2000+ lines. The new services.yaml just has several of these (so far):

App\:
    resource: '../src/*'

# Controllers
App\Controller\:
    resource: '../src/Controller'
    autowire: true
    public: true
    tags: ['controller.service_arguments']

# Models
App\Model\:
    resource: '../src/Model/'
    autowire: true
    public: true

// etc

Question: Do you really need to add service definitions to services.yaml for third party vendor classes? And if so, can I get an example of how to do that please? Any advice from anyone who has already upgraded from Symfony 3 to Symfony 4 would be great.

PHP 7.2.0-2+ubuntu16.04.1+deb.sury.org+2 (cli) (built: Dec 7 2017 20:14:31) ( NTS ) Linux Mint 18, Apache2 Ubuntu.

EDIT / FYI:

This is the "Doctrine\ORM\EntityRepository::__construct()" which the ActivationRepository extends:

/**
     * Initializes a new <tt>EntityRepository</tt>.
     *
     * @param EntityManager         $em    The EntityManager to use.
     * @param Mapping\ClassMetadata $class The class descriptor.
     */
    public function __construct(EntityManagerInterface $em, Mapping\ClassMetadata $class)
    {
        $this->_entityName = $class->name;
        $this->_em         = $em;
        $this->_class      = $class;
    }

which is located here:

/vendor/doctrine/orm/lib/Doctrine/ORM/EntityRepository.php

Answer 1

Starting from the 1.8 version of DoctrineBundle, you can extends your class using Doctrine\Bundle\DoctrineBundle\Repository\ServiceEntityRepository instead of Doctrine\ORM\EntityRepository. The result will be the same, but this support the autowire.

Example:

use App\Entity\Activation;
use Doctrine\Bundle\DoctrineBundle\Repository\ServiceEntityRepository;
use Doctrine\Common\Persistence\ManagerRegistry;

class ActivationRepository extends ServiceEntityRepository
{
    public function __construct(ManagerRegistry $registry)
    {
        parent::__construct($registry, Activation::class);
    }

    // ...
}