Since commit [df49428](https://github.com/wikimedia/mediawiki/commit/df49428b90ecfee7e9e7e9ffdcaca440a4375b50), the `$OutputPage::mLinktags` property has been protected. This broke [my hook code](http://nethackwiki.com/mediawiki/index.php?title=User:Ilmari_Karonen/canonical&oldid=57450), which was inspecting the link tag array to see whether the page already had a `rel=canonical` tag before adding one.
This wouldn't be a big issue (as the code needed updating for MW 1.24 anyway), if there was an accessor method that I could use instead, but unfortunately no such method exists. Effectively, as far as extension code is concerned, this field is currently write-only.
I'd thus like to request that either:
* the `mLinktags` (and, while we're at it, `mMetatags` and `mCanonicalUrl`) properties of the OutputPage class should be made public, or
* accessor methods should be added to allow extension code to examine these fields.
(Ps. I managed to rewrite that particular hook not to require access to these OutputPage properties, but it's not quite as fail-safe as it used to be -- there's a chance that the new code may stomp on a `rel=canonical` URL set by a later MediaWiki version or another extension. In any case, I would expect these fields to be of general interest to extension authors, even if they're not strictly necessary for my specific use case.)