Patch to remove:
https://gerrit.wikimedia.org/r/c/mediawiki/core/+/447629
In the course of writing more tests for OutputPage, I came across the two
methods addMetadataLink() and getMetadataAttribute() that didn't make sense
to me. After a bit of digging, I found they were added in 2004 (22f8c4ce)
to support output of Creative Commons and Dublin Core <link rel="meta">
tags. The only thing they do (compared to directly calling addLink()) is
for some reason setting rel="alternate meta" instead of rel="meta" for
the
first link. I didn't find any reason why they should do that, but based on
a nearby comment I speculate it was to work around bugs in some UAs that
were around at that time.
The functionality of outputting these <link> tags was moved to extensions
in 2011 (27c3b22b), while the methods were left in core. Those extensions
(CreativeCommonsRdf and DublinCoreRdf) now call addHeadItem() directly. A
search found no other uses in core or extensions. Any callers could be
trivially changed to use addLink() or another method.
Legoktm points out that getMetadataAttribute() is marked public, and
therefore strictly speaking can only be removed via the deprecation
policy. (Although getMetadataAttribute() is really just a helper function,
and the actual public interface is addMetadataLink() AFAICT.)
Practically speaking, although they aren't hurting anything, I think this
is useless cruft that it's virtually certain nobody ever used, so I suggest
skipping the deprecation period in this case. Does anyone object?