Laravel 4.2 HHVM 3.6.1 (Ubuntu 14)

Getting an ugly problem filling up log files using HHVM using any kind of cache driver (our tests are File and Memcached). Appears related to the way Laravel sets the cache expiry with Carbon.

Doesn't happen on Vagrant, or OS X.

The following code:

Cache::put('cache_item_name', $data, 10); // or
Cache::add('cache_item_name', $data, 10); // or

$expiresAt = Carbon::now()->addMinutes(10);
Cache::put('cache_item_name', $data, $expiresAt);

Generates this bizarre error:

production.ERROR: exception 'InvalidArgumentException' with message 'Unknown setter 'date'' in /var/www/webapp/server/vendor/nesbot/carbon/src/Carbon/Carbon.php:556

The offending Carbon part (556):

case 'timezone':
case 'tz':
     $this->setTimezone($value);
break;

Removing the cache line stops the error being logged (obviously). Using different values doesn't help (e.g. int for minutes, or expiry seconds). Only occurs with HHVM.

Stack trace:

#0 (): Carbon\Carbon->__set()
#1 (): DateTime->__sleep()
#2 (): Memcached->setByKey()
#3 /var/www/webapp/server/vendor/laravel/framework/src/Illuminate/Cache/MemcachedStore.php(58): Memcached->set()
#4 /var/www/webapp/server/vendor/laravel/framework/src/Illuminate/Cache/Repository.php(94): Illuminate\Cache\MemcachedStore->put()
#5 (): Illuminate\Cache\Repository->put()
#6 /var/www/webapp/server/bootstrap/compiled.php(8296): call_user_func_array()
#7 /var/www/webapp/server/bootstrap/compiled.php(3267): Illuminate\Support\Manager->__call()
#8 /var/www/webapp/server/app/modules/vms/controllers/ActivityController.php(68): Illuminate\Support\Facades\Facade::__callStatic()
#9 (): Vms\Controllers\ActivityController->show_team_newsfeed()
#10 /var/www/webapp/server/vendor/laravel/framework/src/Illuminate/Routing/Controller.php(231): call_user_func_array()
#11 /var/www/webapp/server/bootstrap/compiled.php(5843): Illuminate\Routing\Controller->callAction()
#12 /var/www/webapp/server/bootstrap/compiled.php(5831): Illuminate\Routing\ControllerDispatcher->call()
#13 /var/www/webapp/server/bootstrap/compiled.php(5036): Illuminate\Routing\ControllerDispatcher->dispatch()
#14 (): Closure$Illuminate\Routing\Router::getClassClosure()
#15 /var/www/webapp/server/bootstrap/compiled.php(5394): call_user_func_array()
#16 /var/www/webapp/server/bootstrap/compiled.php(5061): Illuminate\Routing\Route->run()
#17 /var/www/webapp/server/bootstrap/compiled.php(5049): Illuminate\Routing\Router->dispatchToRoute()
#18 /var/www/webapp/server/bootstrap/compiled.php(715): Illuminate\Routing\Router->dispatch()
#19 /var/www/webapp/server/bootstrap/compiled.php(696): Illuminate\Foundation\Application->dispatch()
#20 /var/www/webapp/server/bootstrap/compiled.php(7821): Illuminate\Foundation\Application->handle()
#21 /var/www/webapp/server/bootstrap/compiled.php(8428): Illuminate\Session\Middleware->handle()
#22 /var/www/webapp/server/bootstrap/compiled.php(8375): Illuminate\Cookie\Queue->handle()
#23 /var/www/webapp/server/bootstrap/compiled.php(11040): Illuminate\Cookie\Guard->handle()
#24 /var/www/webapp/server/bootstrap/compiled.php(657): Stack\StackedHttpKernel->handle()
#25 /var/www/webapp/server/public/index.php(50): Illuminate\Foundation\Application->run()
#26 {main} [] []