Magento not clearing interceptor class cache

[jameswithers]

In my etc/adminhtml/di.xml I have

    <type name="Vendor\Module\Controller\Adminhtml\Controller\Action">
        <arguments>
            <argument name="registry" xsi:type="object">Magento\Framework\Registry</argument>
        </arguments>
    </type>  

as I'm trying to pass the registry to the constructor:

namespace Vendor\Module\Controller\Adminhtml\Controller;

class Action extends \Magento\Backend\App\Action
{
    protected $_registry = null;
    /* @var $_registry \Magento\Framework\Registry */

    public function __construct(
            \Magento\Backend\App\Action\Context $context,
            \Magento\Framework\Registry $registry)
    {
        $this->_registry = $registry
        parent::__construct($context);
    }

However I get this error:

a:4:{i:0;s:404:"Recoverable Error: Argument 2 passed to Vendor\Module\Controller\Adminhtml\Controller\Action::__construct() must be an instance of Magento\Framework\Registry, none given...

With Xdebug I can see that $context is being passed fine, but there is nothing there for $registry.

[kandy]

Did you try run command bin/magento cache:flush?

[jameswithers]

@kandy cache is disabled but I ran that command anyway. Still get the same error even when moving di.xml to etc making it global.

[Vinai]

I think you don't actually have to configure the argument in di.xml at all, since the object type is already specified as the type in the constuctor, and all the preference does is try to set the same type again.
Does it work if you delete the section of the di.xml?

[jameswithers]

@kandy @Vinai Got it resolved, but it highlighted another problem (issue title edited to reflect).

The interceptor class Magento had generated was using an old constructor, without registry present.

Frustratingly, clearing the Magento cache had not cleared var/generation/Vendor/Module. Manually deleting this cache meant the interceptor was re-generated, and it now works.

I could not find any reference to this http://devdocs.magento.com/guides/v2.0/extension-dev-guide/depend-inj.html or http://devdocs.magento.com/guides/v2.0/config-guide/config/caching.html and am currently resorting to deleting var/generation each time I make a change.

[kandy]

@jameswithers, did you enable developer mode?

[jameswithers]

@kandy no I did not. I assume this would stop the interceptor class caching? Is there a Magento2-way to clear this cache too? I could not find it in the documentation.

[turgayozgur]

Delete "magento2/var/generation/ModuleName" works for me.

[daim2k5]

The GitHub issue tracker is intended for technical issues only. Please refer to the Community Forums or Magento Stack Exchange site for technical questions. In your case, the programming questions forum is likely the most appropriate. Feel free to reopen this issue if you think you have encountered a bug in Magento 2.