Note: this only works reliably with lexical binding mode, except for very
simple PLACEs such as (function-symbol 'foo) which will also work in dynamic
binding mode."
- (gv-letplace (getter setter) place
- `(cons (lambda () ,getter)
- (lambda (gv--val) ,(funcall setter 'gv--val)))))
+ (let ((code
+ (gv-letplace (getter setter) place
+ `(cons (lambda () ,getter)
+ (lambda (gv--val) ,(funcall setter 'gv--val))))))
+ (if (or lexical-binding
+ ;; If `code' still starts with `cons' then presumably gv-letplace
+ ;; did not add any new let-bindings, so the `lambda's don't capture
+ ;; any new variables. As a consequence, the code probably works in
+ ;; dynamic binding mode as well.
+ (eq (car-safe code) 'cons))
+ code
+ (macroexp--warn-and-return
+ "Use of gv-ref probably requires lexical-binding"
+ code))))
(defsubst gv-deref (ref)
"Dereference REF, returning the referenced value.