TYPO3 Core

Can you post a sample TCA?

https://review.typo3.org/#/c/35483/4/typo3/sysext/backend/Tests/Unit/Utility/BackendUtilityTest.php
Already contains such a testcase, right?

$GLOBALS['TCA'] = array(
    'index_config' => array(
        'columns' => array(
            'indexcfgs' => array(
                'config' => array(
                    'type' => 'group',
                    'internal_type' => 'db',
                    'allowed' => 'index_config,pages',
                    'size' => 5,
                ),
            ),
        ),
    ),
);

Anonymized TCA:

        'category' => array(
            'exclude' => 1,
            'label' => 'LLL:EXT:extkey/locallang_db.xml:tx_extkey.category',
            'config' => array(
                'type' => 'group',
                'internal_type' => 'db',
                'allowed' => 'tx_extkey_cat',
                'size' => 5,
                'minitems' => 0,
                'maxitems' => 100,
                'MM' => "tx_extkey_category_mm",
            )
        ),

adding a line 'foreign_table' => 'tx_extkey_cat', makes the category labels appear in the List module.

The new unit test doesn't have an 'MM' property set. Without 'MM' a different block of code is used which looks in $theColConf['allowed'].
If you look at the new code it explicitly uses $theColConf['foreign_table'] to get the name of the linked table, whereas the old code used $theColConf['allowed'].

allowed can contain a list of tables or '*' as a wildcard, so it is rather complicated to handle them exactly list the 'foreign_table' property of a 'select' field.

Looking at the differences and the definitions in TCAref. I suspect that the previous bugfix was done for extbase extensions since extbase uses 'foreign_table' to find the table name for a 'group' field.

We could easily copy 'allowed' to 'foreign_table' if the latter is empty, but for 'group' fields the options to have multiple foreign tables or a '*' wildcard must still be supported.