Use array_map.

taylorotwell · taylorotwell · commit ce97199ab01b · 2014-02-28T14:28:45.000-06:00
diff --git a/src/Illuminate/Database/Eloquent/Relations/BelongsToMany.php b/src/Illuminate/Database/Eloquent/Relations/BelongsToMany.php
@@ -584,7 +584,7 @@ public function sync(array $ids, $detaching = true)
 		{
 			$this->detach($detach);
 
-			$changes['detached'] = (array) array_walk($detach, 'intval');
+			$changes['detached'] = (array) array_map('intval', $detach);
 		}
 
 		// Now we are finally ready to attach the new records. Note that we'll disable

Original file line number	Diff line number	Diff line change
`@@ -584,7 +584,7 @@ public function sync(array $ids, $detaching = true)`
`584`	`584`	`{`
`585`	`585`	`$this->detach($detach);`
`586`	`586`
`587`		`- $changes['detached'] = (array) array_walk($detach, 'intval');`
	`587`	`+ $changes['detached'] = (array) array_map('intval', $detach);`
`588`	`588`	`}`
`589`	`589`
`590`	`590`	`// Now we are finally ready to attach the new records. Note that we'll disable`