When I suggested that we drop support for Emacs releases before 28.1 and start using shorthands, I mentioned that I don't think it's urgent that we do that.
I changed my mind. Last week, whenever I tried to work on Hyperdrive, I felt an irresistible urge to shorten long lines first, only to abort each time, because in some cases that would lead to some rather ugly line-wrapping. Personally I would still prefer that, but I understand that tastes are different.
A lot of that line wrapping won't be necessary anymore once we switch to using shorthands.
So I propose we do the following, as soon as possible, and in this order.
I would be happy to do 4 and 5. I can also do 3, but if there is backward compatibility that is not explicitly marked as such, I might miss it, since I am not that familiar with the code yet. So someone else might want to do that part.
What do you think, now that you had a week to think about it -- has the time for Emacs 28 and shorthands come yet? I seemed you were all very much on board -- after all I was the only one who didn't want to do it immediately. ;)
FFR: Jonas submitted this bug report to Emacs: shorthands-font-lock-shorthands assumes shorthand uses same separator
Merged into master in 902e52ad!