Re: Building Emacs overflowed pure space

[Stefan Monnier]

>>> So it is safe to take the cdr at the end.
>> 
>> Maybe it is, but it will subtly change the semantics in case the loop body
>> modifies the list it's loooping over.

> But that subtle difference already exists between the cl and subr versions.
> IMO, we better make them consistent.

> As you point out, it is not safe to move the `cdr' if BODY modifies
> the list.  But we could just document this fact in the docstring, e.g.:

> dolist is a Lisp macro in `subr.el'.
> (dolist (var list [result]) body...)

> Loop over a list.
> Evaluate BODY with VAR bound to each car from LIST, in turn.
> Then evaluate RESULT to get return value, default nil.
> The result is undefined if BODY modifies the list.

Sure.  But I currently see no reason to prefer the cl-macs.el behavior over
the subr.el one (AFAICT my suggested code is just as efficient as the
cl-macs.el one), so I'm not sure whether we should change cl-macs.el or
subr.el's behavior.


        Stefan