As described in T220696#5653419 we would like to use the comment_data field from the comments table to generate better edit summaries.
To make comment_data usable it needs to be exposed through the FormatAutocomments hook and stay backwards-compatible. This hook is run from Linter::formatComment which is in turn called from the following files:
Calls to Linker::formatComment
extensions/Wikibase/client/includes/RecentChanges/ChangeLineFormatter.php
includes/DummyLinker.php
includes/FeedUtils.php
includes/Linker.php
includes/actions/RollbackAction.php
includes/api/ApiComparePages.php
includes/api/ApiParse.php
includes/api/ApiQueryDeletedrevs.php
includes/api/ApiQueryFilearchive.php
includes/api/ApiQueryImageInfo.php
includes/api/ApiQueryLogEvents.php
includes/api/ApiQueryProtectedTitles.php
includes/api/ApiQueryRecentChanges.php
includes/api/ApiQueryRevisionsBase.php
includes/api/ApiQueryUserContribs.php
includes/api/ApiQueryWatchlist.php
includes/page/ImageHistoryList.php
includes/specials/pagers/BlockListPager.php
includes/specials/pagers/ImageListPager.php
includes/specials/pagers/ProtectedPagesPager.php
Calls to Linker::revComment (which is itself calling Linker::formatComment)
includes/Revision.php
Calls to Linker::commentBlock (which is itself calling Linker::formatComment)
includes/DummyLinker.php
includes/EditPage.php
includes/actions/McrUndoAction.php
includes/changes/ChangesList.php
includes/logging/LogFormatter.php
includes/revisiondelete/RevDelFileItem.php
includes/revisiondelete/RevDelLogItem.php
includes/specials/SpecialUndelete.php
The above are only the relevant calls from mediawiki/core and wikibase itself.