TYPO3 Core

Topic
In a site with multiple languages and fallback chains configured, extbase models retrieved by an extbase repository do not respect the configured fallback chains.

Example

SiteConfig (only relevant parts):

languages:
  -
    title: 'English (Global)'
    enabled: true
    languageId: 0
    base: /en/
  -
    title: ES-ES
    enabled: true
    base: /es-es/
    typo3Language: es
    fallbackType: strict
    flag: es
    languageId: 15
  -
    title: 'AR-ES'
    enabled: true
    base: /es-ar/
    typo3Language: es
    fallbackType: fallback
    fallbacks: 15
    languageId: 5

Extbase Models in DB:

uid, sys_language_uid, title, l10n_parent
1, 0, 'Model 1 global', 0
2, 15, 'Model 1 spanish', 1
3, 0, 'Model 2 global', 0
4, 5, 'Model 2 spanish argentina', 3
5, 15, 'Model 2 spanish', 3

Using an extbase repository $repository->findAll() returns the following results in language=5:

1, 0, 'Model 1 global', 0
4, 5, 'Model 2 spanish argentina', 3

instead of the expected result:

2, 15, 'Model 1 spanish', 1
4, 5, 'Model 2 spanish argentina', 3

I've tracked the problem down to
\TYPO3\CMS\Extbase\Persistence\Generic\Storage\Typo3DbBackend->overlayLanguageAndWorkspaceForSingleRecord

in line 540 a new instance of LanguageAspect is created but without handing over the fallbackChain of the original languageAspect:

$customLanguageAspect = new LanguageAspect($languageUid, $languageUid, LanguageAspect::OVERLAYS_MIXED);
$row = $pageRepository->getLanguageOverlay($tableName, $row, $customLanguageAspect);

I am not sure, if this is done with purpose, but the pageRepository further more does not know about the configured fallbackChain and so cannot return the correct record. In my opinion the above code should look like this:

$customLanguageAspect = new LanguageAspect($languageUid, $languageUid, LanguageAspect::OVERLAYS_MIXED, $languageAspect->getFallbackChain());
$row = $pageRepository->getLanguageOverlay($tableName, $row, $customLanguageAspect);