GNU bug report logs - #16816
24.3.50; erroneous docstring in with-temp-buffer-window

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Message #20 received at 16816 <at> debbugs.gnu.org (full text, mbox):

From: martin rudalics <rudalics <at> gmx.at>
To: Juanma Barranquero <lekktu <at> gmail.com>
Cc: Nicolas Richard <theonewiththeevillook <at> yahoo.fr>, 16816 <at> debbugs.gnu.org
Subject: Re: bug#16816: 24.3.50; erroneous docstring in with-temp-buffer-window
Date: Thu, 27 Feb 2014 19:44:55 +0100

> This breaks with-help-window. Try
>
>  emacs -Q
>  C-x C-h
>
> the help output is inserted in the current buffer (*scratch*, in this case).

Yes.  A lousy bug.  I introduced it last year relying on the misfeature
that `with-temp-buffer-window' makes the help buffer current.  Does the
following patch fix it?

=== modified file 'lisp/help.el'
--- lisp/help.el	2014-02-10 01:34:22 +0000
+++ lisp/help.el	2014-02-27 18:31:30 +0000
@@ -498,7 +498,8 @@
 then we display only bindings that start with that prefix."
   (let ((buf (current-buffer)))
     (with-help-window (help-buffer)
-      (describe-buffer-bindings buf prefix menus))))
+      (with-current-buffer (help-buffer)
+	(describe-buffer-bindings buf prefix menus)))))

 (defun where-is (definition &optional insert)
   "Print message listing key sequences that invoke the command DEFINITION.

> This patch fixes it.
>
> === modified file 'lisp/help.el'
> --- lisp/help.el 2014-02-10 01:34:22 +0000
> +++ lisp/help.el 2014-02-27 15:29:05 +0000
> @@ -1207,7 +1207,8 @@
>     (temp-buffer-window-show-hook
>      (cons 'help-mode-finish temp-buffer-window-show-hook)))
>         (with-temp-buffer-window
> - ,buffer-name nil 'help-window-setup (progn ,@body)))))
> + ,buffer-name nil 'help-window-setup
> + (with-current-buffer ,buffer-name ,@body)))))
>
>  ;; Called from C, on encountering `help-char' when reading a char.
>  ;; Don't print to *Help*; that would clobber Help history.
>

This would restore what we had till now: BODY would get evaluated in the
help buffer and not in the original buffer.  I doubt this could have any
serious consequences (Emacs 24.3 runs this already for quite some time)
but it's inherently disturbing.

martin

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