Common Lisp in Emacs (lisp-mode, font-lock, SLIME, SLY, ...)

[Stefan Monnier]

Sorry to spam here a little, but I was looking into how we should
integrate something like cl-font-lock
(https://github.com/cl-font-lock/cl-font-lock) into Emacs and then
I started to wonder...

Who uses `lisp-mode`?  IIUC neither SLY nor SLIME actually use
`lisp-mode` itself, they use some other major mode with its
fontification function, right?

So do they already highlight built-in functions, types, and variables in
a special way (presumably by querying the underlying Lisp process)?

Do they actually use a proper child-mode of `lisp-mode`?

Do they (re)use the font-lock keywords of `lisp-mode` at all, or do they
use something completely independent?


        Stefan