Pass the label fields to the label_callback

Contao hands the prepared label fields to a label_callback as a fourth argument,
and its own callbacks declare them as required - "tl_member::addIcon()" is one of
several. We passed three, so every table carrying such a callback was fatal:
picking from tl_member or tl_calendar_events ended in an ArgumentCountError
instead of a list. Callbacks declaring only three parameters are unaffected; PHP
passes the surplus argument and they never look at it.

An array return value is now taken over whatever the list is grouped by. It was
tied to the table mode before, so everywhere else the callback ran and its
result was dropped.

Matching those returned fields by position stays limited to the table mode,
where both sides describe the same columns. Anywhere else they do not: a picker
shows the one property it was configured with, while a Contao callback counts
along its own "label/fields" - tl_member reserves the first of those for the
icon and would push that markup into the picker's only column, replacing the
very value one is meant to pick.

Author: zonky2

src/Contao/Callback/ModelLabelCallbackListener.php

@@ -45,6 +45,12 @@ public function getArgs($event)
             $event->getModel()->getPropertiesAsArray(),
             $event->getLabel(),
             new DcCompat($event->getEnvironment(), $event->getModel()),
+            // Contao hands the prepared label fields over as a fourth argument, and its own
+            // callbacks declare them as required - "tl_member::addIcon()" is one of several.
+            // Without it, every table carrying such a callback was fatal here. Callbacks that
+            // declare only three parameters stay unaffected; PHP passes the surplus argument
+            // and they never look at it.
+            $event->getArgs(),
         ];
     }
 
@@ -53,17 +59,20 @@ public function getArgs($event)
      */
     public function update($event, $value)
     {
-        $groupingInformation = ViewHelpers::getGroupingMode($event->getEnvironment());
-        if (
-            isset($groupingInformation['mode'])
-            && ($groupingInformation['mode'] === GroupAndSortingInformationInterface::GROUP_NONE)
-        ) {
-            if (!\is_array($value)) {
-                return;
-            }
+        if (\is_array($value)) {
             /** @var list<string> $value */
 
-            $this->updateTableMode($event, $value);
+            // An array means the callback handed the label fields back - regardless of how the
+            // list happens to be grouped. Tying this to the table mode dropped the return value
+            // everywhere else, which is why a Contao callback left the label empty.
+            $groupingInformation = ViewHelpers::getGroupingMode($event->getEnvironment());
+            $isTableMode         =
+                isset($groupingInformation['mode'])
+                && ($groupingInformation['mode'] === GroupAndSortingInformationInterface::GROUP_NONE);
+
+            $this->updateArguments($event, $value, $isTableMode);
+
+            return;
         }
 
         if (!\is_string($value)) {
@@ -100,31 +109,42 @@ private function updateNonTableMode(ModelToLabelEvent $event, ?string $value): v
     }
 
     /**
-     * Set the value in the event.
+     * Take the label fields a callback returned over into the event.
      *
-     * @param ModelToLabelEvent   $event     The event being emitted.
-     * @param string|list<string> $arguments The label arguments.
+     * @param ModelToLabelEvent   $event       The event being emitted.
+     * @param string|list<string> $arguments   The label arguments.
+     * @param bool                $byPosition  Whether numeric keys may be matched by position.
      *
      * @return void
      */
-    private function updateTableMode(ModelToLabelEvent $event, array|string $arguments): void
+    private function updateArguments(ModelToLabelEvent $event, array|string $arguments, bool $byPosition): void
     {
         if (empty($arguments)) {
             return;
         }
 
         $updateArguments = $event->getArgs();
 
-        // Step 1 update arguments by index as propertyName
-        foreach ($event->getFormatter()->getPropertyNames() as $index => $propertyName) {
+        // By name - this always means the same field on both sides.
+        foreach ($event->getFormatter()->getPropertyNames() as $propertyName) {
             if (!isset($arguments[$propertyName])) {
                 continue;
             }
 
             $updateArguments[$propertyName] = $arguments[$propertyName];
         }
 
-        // Step 2 update arguments by index as integer
+        // By position - only where both sides describe the same list of columns, which is the
+        // table mode. Anywhere else the two have nothing to do with each other: a picker shows
+        // the one property it was configured with, while a Contao callback counts along its own
+        // "label/fields" - "tl_member" reserves the first of those for the icon and would push
+        // that markup into the picker's only column, replacing the value one is meant to pick.
+        if (!$byPosition) {
+            $event->setArgs($updateArguments);
+
+            return;
+        }
+
         foreach ($event->getFormatter()->getPropertyNames() as $index => $propertyName) {
             if (!isset($arguments[$index])) {
                 continue;