Thank you everyone for the good discussion and ideas! It sounds like there’s general agreement that Announcements is a good place to put this information and use a tag to distinguish potentially breaking change announcements from other kinds of announcements. I think it also makes sense to start adding clang-vendors as a subscriber to any Clang code review we think may impact vendors. Between all of these mechanisms (and the fact that we’re announcing potentially breaking changes more clearly in the release notes), I think we’ve made some really good steps at improving communication with our users.
I have some breaking changes from the release notes to announce, so I’ll make the inaugural post and put it under the tags potential-disruption and clang; other projects that want to make similar announcements can use their own project’s tag.