Faster and more robust list-of-strings-p

* lisp/subr.el (list-of-strings-p): Speed up by a factor 4 (approx.)
and don't crash on dotted lists.
* test/lisp/subr-tests.el (test-list-of-strings-p): Extend test.

1 files changed, 3 insertions, 2 deletions

diff --git a/lisp/subr.el b/lisp/subr.el
index e8e8f1584b4..caea2b9f933 100644
--- a/lisp/subr.el
+++ b/lisp/subr.el
@@ -4028,8 +4028,9 @@ Otherwise, return nil."
 
 (defun list-of-strings-p (object)
   "Return t if OBJECT is nil or a list of strings."
-  (and (listp object)
-       (seq-every-p #'stringp object)))
+  (while (and (consp object) (stringp (car object)))
+    (setq object (cdr object)))
+  (null object))
 
 (defun booleanp (object)
   "Return t if OBJECT is one of the two canonical boolean values: t or nil.