Implement calculateDependencies() in ArgumentPluginBase to get dependencies from validator and default plugins

We should've unpostponed this a long time ago.

Should this be critical?

Yeah there are probably config dependencies in there. :)

Well, I have seen major issues which have been way more critical, anyway.

Patch looks sane. Needs tests?

I looked into adding content entity dependencies for when you provide a fixed argument for something like a UID or NID. Since it is perfectly possible to put non existent IDs here and they are not converted to UUIDs I think that is beyond the scope here and might even be undesirable.

Yeah, the problem is that you don't even know what people might do with the number entered there. It could be that they use it for >comparisons, in which not validating the number as dependency would be the thing you want

Sounds like validation fun time in a child issue of #2392823: [meta] Much Views UI input is not validated.

For the specific entity dependencies, I do think that's worth a followup since the 80% usecase probably is referencing a specific entity, and the default argument could be a config or content entity depending on the plugin. It might wait on the entity referencing widget bit we talked about as a followup for #2341357: Views entity area config is not deployable and missing dependencies.

Thank you alex for writing a test!

Let's expand the test coverage to argument validator plugins as well.

Forgot one new file.

This is beautiful and elegant imo so RTBC.

+++ b/core/modules/views/tests/modules/views_test_data/config/schema/views_test_data.views.schema.yml
@@ -95,3 +95,10 @@ views.display_extender.display_extender_test:
+  type: ignore
...
+  type: ignore

I didn't know about that.

+++ b/core/modules/views/src/Plugin/views/argument_validator/Entity.php
@@ -7,11 +7,13 @@
+use Drupal\Component\Plugin\Exception\PluginNotFoundException;
...
+use SebastianBergmann\Exporter\Exception;

Neither of these are used. Removed them.

Committed/pushed to 8.0.x, thanks!