Proposal:
There should be an option to protect a page from //viewing//, in addition to the current edit/move/upload/create protection options
Use case:
* Allow restricting viewing abuse filters (for T227595)
* Allow revealing information to specific users for WikiJournal (https://meta.wikimedia.org/wiki/WikiJournal/Technical_wishlist)
* T160266 (restricted, so I don't have access)
* ...
Background
https://www.mediawiki.org/wiki/Security_issues_with_authorization_extensions
Acceptance criteria:
Read protection or restrictions should be apply to be applied to a page or a namespace. Users must have the relevant rights to:
* Export the page
* View the page, the page history, or the page content
* Edit the page
* Move the page
* The page should either not be transcluded, or the same view restriction should extend to its transclusion
In addition, the feature must work efficiently with any supported types of caches