The logic in ExtensionRegistry and ExtensionProcessor is very much like the logic in SettingsBuilder. Similarly, the idea and structure of settings files is very much like extension.json files.
Ideally, we should use the same mechanism for loading settings files and extension definitions. This would ensure consistent behavior and minimize code duplication.
Change 740367 had a related patch set uploaded (by Daniel Kinzler; author: Daniel Kinzler):
[mediawiki/core@master] WIP: load extensions via SettingsBuilder
Change 745613 had a related patch set uploaded (by Daniel Kinzler; author: Daniel Kinzler):
[mediawiki/core@master] Convert extension.json to settings file format.
Change 769489 had a related patch set uploaded (by Daniel Kinzler; author: Daniel Kinzler):
[mediawiki/core@master] Integration test for extension registration
Change 769489 merged by jenkins-bot:
[mediawiki/core@master] Integration test for extension registration