diff options
Diffstat (limited to 'lisp/emacs-lisp/byte-opt.el')
| -rw-r--r-- | lisp/emacs-lisp/byte-opt.el | 11 |
1 files changed, 10 insertions, 1 deletions
diff --git a/lisp/emacs-lisp/byte-opt.el b/lisp/emacs-lisp/byte-opt.el index da997212eef..0f7a3cb2665 100644 --- a/lisp/emacs-lisp/byte-opt.el +++ b/lisp/emacs-lisp/byte-opt.el @@ -1531,7 +1531,16 @@ See Info node `(elisp) Integer Basics'." (prev (car newargs))) (cond ;; Elide null args. - ((null arg) (loop (cdr args) newargs)) + ((and (null arg) + ;; Don't elide a terminal nil unless preceded by + ;; a nonempty proper list, since that will have + ;; its last cdr forced to nil. + (or (cdr args) + ;; FIXME: prove the 'nonempty proper list' property + ;; for more forms than just `list', such as + ;; `append', `mapcar' etc. + (eq 'list (car-safe (car newargs))))) + (loop (cdr args) newargs)) ;; Merge consecutive `list' args. ((and (eq (car-safe arg) 'list) (eq (car-safe prev) 'list)) |