Clarify what counts as whitespace in `string-blank-p'

* lisp/emacs-lisp/subr-x.el (string-blank-p): Expand doc string.

diff --git a/lisp/emacs-lisp/subr-x.el b/lisp/emacs-lisp/subr-x.el
index f76409c4de87ed67acf0ec643a04f999ad7f1b7f..bb2bf3dd5facc70263b1b7392c8cd3178c0bf042 100644 (file)
--- a/lisp/emacs-lisp/subr-x.el
+++ b/lisp/emacs-lisp/subr-x.el
@@ -236,7 +236,9 @@ TRIM-LEFT and TRIM-RIGHT default to \"[ \\t\\n\\r]+\"."
   (string-trim-left (string-trim-right string trim-right) trim-left))
 
 (defsubst string-blank-p (string)
-  "Check whether STRING is either empty or only whitespace."
+  "Check whether STRING is either empty or only whitespace.
+The following characters count as whitespace here: space, tab, newline and
+carriage return."
   (string-match-p "\\`[ \t\n\r]*\\'" string))
 
 (defsubst string-remove-prefix (prefix string)