[03:13:07] <Krinkle>	 TimStarling: I'm looking into https://gerrit.wikimedia.org/r/c/mediawiki/core/+/890872 and concluding two things:
[03:13:18] <Krinkle>	 Both conclusions based on CommentParser.php
[03:16:56] <Krinkle>	 1. Changing callers that already LinkBatch from makeKnownLink to makeLink isn't as trivial as I thought, because it also means incurring onTitleIsAlwaysKnown and onTitleExists hooks), which is functionally correct but not as clear cut. Using CommentParser, it already invokes onTitleIsAlwaysKnown, but simplifying the code to linkCache->isGood/isBad and then calling makeLink changes performance in that it would now call isAlwaysKnown first 
[03:16:57] <Krinkle>	 (and it hook) before it gets to exists() and the in-object or linkCache'd pageId. That looks like something we could optimise more generally perhaps if that was significant enough to do in CommentParser. (It's not obvious from your commit that it was motiviated by performance though, because you orignally wrote linkCachce->isGood or isExternal, and then it was changed by subsequent commits to what we had today to fix a functional issue).
[03:17:52] <Krinkle>	 2. CommentParser actuall skips the onTitleExists hook entirely. And... this appears insignificant because not one thing in Codesearch Everywhere uses this hook. It was only recently added in 1.35. Maybe we should get rid of that and tell however added it to use onTitleIsAlwaysKnown instead.
[03:19:59] <Krinkle>	 My search query didn't catch programmatic usage in tests, there are two and there is TemplateSandbox. https://codesearch.wmcloud.org/search/?q=%5B%27%22%5DTitleExists&i=nope&files=&excludeFiles=&repos=
[03:21:04] <Krinkle>	 indeed added for TemplateSandbox. https://gerrit.wikimedia.org/r/c/mediawiki/core/+/160546
[03:21:48] <Krinkle>	 ref T265775
[03:21:49] <stashbot>	 T265775: Retire TitleExists hook - https://phabricator.wikimedia.org/T265775