setFetchMode does not respect second level association

[aalgogiver]

Bug Report

Q	A
BC Break	no
Version	3.2.1

Summary

Calling setFetchMode with ClassMetadata::FETCH_EAGER does not respect second level association.

Current behavior

When I add the following testing method to tests/Tests/ORM/Functional/BasicFunctionalTest.php it fails

    public function testManyToOneSecondLevelEagerAssociationWithSetFetchMode(): void
    {
        $user           = new CmsUser();
        $user->username = 'beberlei';
        $user->name     = 'Benjamin E.';
        $user->status   = 'active';

        $article1        = new CmsArticle();
        $article1->topic = 'foo';
        $article1->text  = 'bar';
        $article1->user  = $user;

        $article2        = new CmsArticle();
        $article2->topic = 'bar';
        $article2->text  = 'foo';
        $article2->user  = $user;

        $comment1 = new CmsComment();
        $comment1->article = $article1;
        $comment1->topic = 'foo';
        $comment1->text = 'comment1';

        $comment2 = new CmsComment();
        $comment2->article = $article2;
        $comment2->topic = 'bar';
        $comment2->text = 'comment2';

        $this->_em->persist($article1);
        $this->_em->persist($article2);
        $this->_em->persist($comment1);
        $this->_em->persist($comment2);
        $this->_em->persist($user);
        $this->_em->flush();
        $this->_em->clear();

        $this->getQueryLog()->reset()->enable();
        $dql   = 'SELECT u FROM Doctrine\Tests\Models\CMS\CmsUser u';
        $users = $this->_em->createQuery($dql)
                             ->setFetchMode(CmsUser::class, 'articles', ClassMetadata::FETCH_EAGER)
                             ->setFetchMode(CmsArticle::class, 'comments', ClassMetadata::FETCH_EAGER)
                             ->getResult();

        foreach ($users as $user) {
            foreach ($user->articles as $article) {
                $article->comments->initialize();
            }
        }

        // 1 query for users, 1 for articles, 1 for comments and 1 for addresses (CmsUser::$address relation)
        $this->assertQueryCount(4);
    }

and produces 5 queries instead of expected 4 due to fetching comments separately for each article.

How to reproduce

Use the code snippet above.

Expected behavior

Should work in a similar way to the following passing test when relation's mode is being set explicitly.

    public function testManyToOneSecondLevelEagerAssociationWithClassMetadata(): void
    {
        $user           = new CmsUser();
        $user->username = 'beberlei';
        $user->name     = 'Benjamin E.';
        $user->status   = 'active';

        $article1        = new CmsArticle();
        $article1->topic = 'foo';
        $article1->text  = 'bar';
        $article1->user  = $user;

        $article2        = new CmsArticle();
        $article2->topic = 'bar';
        $article2->text  = 'foo';
        $article2->user  = $user;

        $comment1 = new CmsComment();
        $comment1->article = $article1;
        $comment1->topic = 'foo';
        $comment1->text = 'comment1';

        $comment2 = new CmsComment();
        $comment2->article = $article2;
        $comment2->topic = 'bar';
        $comment2->text = 'comment2';

        $this->_em->persist($article1);
        $this->_em->persist($article2);
        $this->_em->persist($comment1);
        $this->_em->persist($comment2);
        $this->_em->persist($user);
        $this->_em->flush();
        $this->_em->clear();

        $classMetadata = $this->_em->getClassMetadata(CmsArticle::class);

        $fetchMode = $classMetadata->associationMappings['comments']['fetch'];
        $classMetadata->associationMappings['comments']['fetch'] = ClassMetadata::FETCH_EAGER;

        $this->getQueryLog()->reset()->enable();
        $dql   = 'SELECT u FROM Doctrine\Tests\Models\CMS\CmsUser u';
        $users = $this->_em->createQuery($dql)
                             ->setFetchMode(CmsUser::class, 'articles', ClassMetadata::FETCH_EAGER)
                             ->getResult();

        $classMetadata->associationMappings['comments']['fetch'] = $fetchMode;

        foreach ($users as $user) {
            foreach ($user->articles as $article) {
                $article->comments->initialize();
            }
        }

        // 3 separate queries for users, articles, comments and 1 for addresses
        $this->assertQueryCount(4);
    }