Add value objects to represent the return of hook_requirements

+++ b/core/lib/Drupal/Core/Extension/Requirement/RequirementInterface.php
@@ -0,0 +1,107 @@
+  const SEVERITY_OK = 0;
...
+  const SEVERITY_INFO = -1;
...
+  const SEVERITY_ERROR = 2;
...
+  const SEVERITY_WARNING = 1;

Instead of constants it could be enum or even removed in favour of methods (like accessResult doing).
But this weight used only for frontend to group sort requirements - that usage is missing in replacement

We could possibly roll this into 📌 Add value objects to represent the return of hook_requirements Needs work

Converted to a single Requirement class with enums for RequirementSeverity and RequirementPhase.

Remaining tasks:

• Decide if we should just enforce required properties by using constructor args
• Ensure sorting works
• Replace usages of requirements arrays

Hiding old patches

Seems to have some test failures.

I think this issue is quite large, having to convert all of cores hook requirements to value objects as well as handle deprecations.

We should split out the smaller task of creating enums for RequirementSeverity and RequirementPhase 📌 Create enums for RequirementSeverity and RequirementPhase Active

📌 Replace hook_requirements with tagged services Active is two thirds done.

If we can get this also into 11.2 then this might considerably simplify the BC layer. New hook use value objects, old hooks use arrays, we just need to merge it together in the places where core calls both the old and the new hooks?

Agreed this would be great to do in 11.2.0 so the new hooks only use the new API. Tagging as such. But this should now be postponed on 📌 Create enums for RequirementSeverity and RequirementPhase Active , no?

📌 Create enums for RequirementSeverity and RequirementPhase Active is merged

Rebased on 11.x

Several failures, this definitely won't make it in for 11.2 I think.

Personally I would want to postpone this in the system_requirements conversion. That issue was green and just need to take the new enum into account.

I'll link it later when I fix that issue.

Damn. I wish I saw your comment before I started converting system_requirements() 😓

I pushed up my work in progress in case it's useful later.