At least $wgWBClientDataTypes is, as far as I can tell, not used externally – other extensions that add data types use the WikibaseClientDataTypes hook for that instead of manipulating the global directly, which is very nice. (Though I imagine we could also use attributes instead, if we wanted to.)

Edit: and the same seems to be true for $wgWBRepoDataTypes, so I would try to get rid of both of those globals at once – otherwise there’s some documentation like “$wgWBRepoDataTypes resp. $wgWBClientDataTypes” which we’d have to awkwardly rephrase because the two settings would work differently.

Decided to create a separate subtask for $wgWBClientDataTypes so it’s clearer that I’m not picking up the $wgWBClientSettings part (yet) – that’s still free for anyone else to pick up.

Edit: and apparently new subtasks don’t show up in the task activity (between the comments) anymore? anyways it’s T256756: Remove $wgWBRepoDataTypes and $wgWBClientDataTypes global variables

Change 608663 had a related patch set uploaded (by Lucas Werkmeister (WMDE); owner: Lucas Werkmeister (WMDE)):
[mediawiki/extensions/Wikibase@master] WIP: Don’t load $wgWBClientSettings in WikibaseClient.php

https://gerrit.wikimedia.org/r/c/mediawiki/extensions/Wikibase/ /608663

I quite like the appraoch. I wish we could rebuild the configs with config registry, it would have been awesome: https://www.mediawiki.org/wiki/Manual:Configuration_for_developers

But it's lot of work, specially since the Config object is immutable and our objects (SettingsArray) is not (which is not good, I don't want the configuration change dynamically at middle of code run).

Yeah, I don’t think using the config registry is feasible for this sprint. The most significant missing feature is probably lazy initialization of values – in Wikibase, a lot of the settings are callbacks that compute the setting on-demand, which isn’t supported by MediaWiki’s Config system as far as I’m aware.

I added a test to my change for $wgWBClientSettings, and removed a TODO. I think it’s ready for proper review now. (Still feels very risky, though, I’ll be honest.)

Change 608663 merged by jenkins-bot:
[mediawiki/extensions/Wikibase@master] Don’t load $wgWBClientSettings in WikibaseClient.php

https://gerrit.wikimedia.org/r/608663

Change 609794 had a related patch set uploaded (by Lucas Werkmeister (WMDE); owner: Lucas Werkmeister (WMDE)):
[mediawiki/vagrant@master] Remove $wgWBSharedSettings

https://gerrit.wikimedia.org/r/609794

Change 609794 merged by jenkins-bot:
[mediawiki/vagrant@master] Remove $wgWBSharedSettings

https://gerrit.wikimedia.org/r/609794