Stefan Monnier <monnier@iro.umontreal.ca> schrieb am Di., 26. Sep. 2017 um
16:47 Uhr:

>
> Not sure what might break if we do that: the main user of
> cl-symbol-macrolet outside of generator.el AFAIK is the with-slots of
> eieio, so the question is whether some users of with-slots expect
> a subsequent `let` binding to temporarily change the slot's value.
> I just checked and it seems that no code in Emacs itself relies on this
> behavior, so maybe it's "safe" to change it.
>

At least the docstring of `with-slots' and the EIEIO manual both state:
"Both ‘setf’ and ‘setq’ can be used to set the value of the slot." In
particular, it doesn't state that `let' can be used for this purpose. So as
long as `setf' and `setq' continue working, I think it should be OK to
change the behavior (it should still be documented as incompatible Lisp
change though).