Incorrect theme loaded when critical_css module is installed

Looking at the current code in the critical_css module, it disables itself on admin pages. https://git.drupalcode.org/project/critical_css/-/blob/8.x-1.x/src/Asset...

So I don't think the issue description is accurate.

The problem is that Drupal\components\Template\Loader\ComponentsLoader calls
Drupal\Core\Theme\ThemeManager->getActiveTheme() too early and
\Drupal\user\Theme\AdminNegotiator can't correctly determine admin theme because correct RouteMatch is not set yet.

The issue is caused by critical_css because it decorates `asset.css.collection_renderer` service (https://git.drupalcode.org/project/critical_css/-/blob/8.x-1.x/critical_...) and adds twig service as dependency, which later constructs `components.twig.loader` service.

`asset.css.collection_renderer` is used by `ajax_response.attachments_processor` which is used by `ajax_response.subscriber`;

The correct RouteMatch is set by `router_listener`, which has smaller priority than `ajax_response.subscriber`, and is called later (while the active theme is already set)
For this reason we get incorrect theme

Attached a screenshot to display whole chain of services involved.

Thanks, Evaldas! That's super helpful info.

The problem is that Drupal\components\Template\Loader\ComponentsLoader calls
Drupal\Core\Theme\ThemeManager->getActiveTheme() too early

I think this is exactly the cause of the bug.

I looked at how Drupal core's ThemeRegistryLoader works in detail and it causes Drupal\Core\Theme\ThemeManager->getActiveTheme() to be called too, but it doesn't do so during its constructor. It only triggers that method in ThemeRegistryLoader::findTemplate(). We should do the same in ComponentsLoader.

This bug exists in both 3.x and 8.x-2.x.

Fixed in 3.x.

This needs to be backported to 8.x-2.x.

Evaldas and Majid,

Can you check out the latest code on the 8.x-2.x branch and see if that fixes the bug? I haven't tested my fix against the critical_css module.

If the bug is fixed, I can make a new 8.x-2.2 release with the bugfix.

John,

2.x still not work correctly.

There is one more part that calls getActiveTheme (introduced with #3191968: Add alter hook for protected Twig namespaces in 2.1.0)

Drupal\components\Template\ComponentsInfo is calling alter for ThemeManager on construct ( $themeManager->alter('protected_twig_namespaces', $this->protectedNamespaces) ) which is calling getActiveTheme.

Drupal\components\Template\ComponentsInfo is calling alter for ThemeManager on construct ( $themeManager->alter('protected_twig_namespaces', $this->protectedNamespaces) ) which is calling getActiveTheme.

*sigh* ok. Thanks for the new info! It really helps a lot.

So we'll need to add an initialization flag to ComponentsInfo and not init() the namespaces data until ComponentsLoader::findTemplate() is called.

Ok. One more time.

Can you check out the latest code on the 8.x-2.x branch and see if that fixes the bug?

If the bug is fixed, I can make a new 8.x-2.2 release with the bugfix.

It's perfect now, the correct admin theme is activated.

It's perfect now, the correct admin theme is activated.

Thanks for all your help, Evaldas!

https://www.drupal.org/project/components/releases/8.x-2.2