From: Juri Linkov <juri@linkov.net>
Date: Fri, 6 Mar 2020 00:27:32 +0000 (+0200)
Subject: Fix handling of empty input in describe-variable and describe-symbol
X-Git-Tag: emacs-28.0.90~7794
X-Git-Url: http://git.eshelyaron.com/gitweb/?a=commitdiff_plain;h=7e8b8da9e30c8b3dcb2f7740406358e00a1a42f8;p=emacs.git

Fix handling of empty input in describe-variable and describe-symbol

* lisp/help-fns.el (describe-variable): Use 'user-error' like in
'describe-function'.
(describe-symbol): Use empty string for arg SYMBOL when input is empty
and there is no default value.
This allows to signal the error "You didn't specify a function or variable"
instead of displaying help about the symbol 'nil' on empty input.
OTOH, still allows to see help about 'nil' when the input is "nil".
---

diff --git a/lisp/help-fns.el b/lisp/help-fns.el
index 59eedb5331d..cc00c722ccc 100644
--- a/lisp/help-fns.el
+++ b/lisp/help-fns.el
@@ -944,7 +944,7 @@ it is displayed along with the global value."
     (unless (buffer-live-p buffer) (setq buffer (current-buffer)))
     (unless (frame-live-p frame) (setq frame (selected-frame)))
     (if (not (symbolp variable))
-	(message "You did not specify a variable")
+	(user-error "You didn't specify a variable")
       (save-excursion
 	(let ((valvoid (not (with-current-buffer buffer (boundp variable))))
 	      val val-start-pos locus)
@@ -1435,7 +1435,7 @@ current buffer and the selected frame, respectively."
 				t nil nil
 				(if found (symbol-name v-or-f)))))
      (list (if (equal val "")
-	       v-or-f (intern val)))))
+	       (or v-or-f "") (intern val)))))
   (if (not (symbolp symbol))
       (user-error "You didn't specify a function or variable"))
   (unless (buffer-live-p buffer) (setq buffer (current-buffer)))