- (list 'block nil
- (list* 'let (list (list temp (nth 1 spec)) (car spec))
- (list* 'while temp (list 'setq (car spec) (list 'car temp))
- (append body (list (list 'setq temp
- (list 'cdr temp)))))
- (if (cdr (cdr spec))
- (cons (list 'setq (car spec) nil) (cdr (cdr spec)))
- '(nil))))))
+ ;; FIXME: Copy&pasted from subr.el.
+ `(block nil
+ ;; This is not a reliable test, but it does not matter because both
+ ;; semantics are acceptable, tho one is slightly faster with dynamic
+ ;; scoping and the other is slightly faster (and has cleaner semantics)
+ ;; with lexical scoping.
+ ,(if lexical-binding
+ `(let ((,temp ,(nth 1 spec)))
+ (while ,temp
+ (let ((,(car spec) (car ,temp)))
+ ,@body
+ (setq ,temp (cdr ,temp))))
+ ,@(if (cdr (cdr spec))
+ ;; FIXME: This let often leads to "unused var" warnings.
+ `((let ((,(car spec) nil)) ,@(cdr (cdr spec))))))
+ `(let ((,temp ,(nth 1 spec))
+ ,(car spec))
+ (while ,temp
+ (setq ,(car spec) (car ,temp))
+ ,@body
+ (setq ,temp (cdr ,temp)))
+ ,@(if (cdr (cdr spec))
+ `((setq ,(car spec) nil) ,@(cddr spec))))))))