rpav/cffi — comment on commit 77975b7444b6af653195870041081cdaba6503a7
File: src/enum.lisp line 230
By rpav:

I had considered this and originally made the macros check for this, but given the contexts in which it's used, I don't think VALUE will ever usefully be a constant. For instance, this is expanded in a function definition generated by DEFCFUN, where it can only be non-constant. In theory, if DEFCFUN generated a compiler macro, or the SETF form for structure slots was an expander, this could be taken advantage of, but both look to require a rather nontrivial amount of work and testing.

I may of course be overlooking something obvious.