GNU bug report logs - #24573
25.1; Setting bookmark in buffer *Help* makes bookmarks non-loadable

Previous Next

To add a comment to this bug, you must first unarchive it, by sending
a message to control AT debbugs.gnu.org, with unarchive 24573 in the body.
You can then email your comments to 24573 AT debbugs.gnu.org in the normal way.

Toggle the display of automated, internal messages from the tracker.

Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Dmitri Paduchikh <dpaduchikh <at> gmail.com>
To: bug-gnu-emacs <at> gnu.org
Subject: 25.1; Setting bookmark in buffer *Help* makes bookmarks non-loadable
Date: Fri, 30 Sep 2016 19:13:28 +0500

Hello,

I start emacs -q, open the *Help* buffer, set a bookmark there, and save
bookmarks to file. After this I get the following error message while
trying to load bookmarks back.

Saving bookmarks to file ~/.emacs.d/bookmarks...done
Loading bookmarks from ~/.emacs.d/bookmarks...
bookmark-alist-from-buffer: Invalid read syntax: "#"

And indeed, the file contains text #<buffer *GNU Emacs*>. Replacing this
by nil manually fixes the problem.

;;;; Emacs Bookmark Format Version 1 ;;;;
;;; This format is meant to be slightly human-readable;
;;; nevertheless, you probably don't want to edit it.
;;; -*- End Of Bookmark File Format Version Stamp -*-
(("car"
 (position . 49)
 (help-fn .
	  #[514 "\301.!\205.\211.\302.!)\207"
		[describe-function-orig-buffer buffer-live-p describe-function]
		4 "\n\n(fn FUNCTION BUFFER)"])
 (help-args car #<buffer *GNU Emacs*>)
 (position . 49)
 (handler . help-bookmark-jump))
)


In GNU Emacs 25.1.1 (x86_64-unknown-linux-gnu, GTK+ Version 3.20.9)
 of 2016-09-18 built on juergen

Regards,
Dmitri Paduchikh

Message #8 received at 24573 <at> debbugs.gnu.org (full text, mbox):

From: Win Treese <treese <at> acm.org>
To: 24573 <at> debbugs.gnu.org
Cc: Win Treese <treese <at> acm.org>
Subject: Re: 25.1; Setting bookmark in buffer *Help* makes bookmarks
 non-loadable
Date: Sat, 28 Oct 2017 14:53:59 -0400

I ran into the same problem.

To reproduce:

1. C-h f find-file

2. In the *Help* buffer:

    C-x r m  ; create a bookmark to the help for find-file

3. Exit Emacs (which should save the bookmark)

4. In a fresh Emacs,
   C-x r b    ; to visit any bookmark

This results in an error:

   bookmark-alist-from-buffer: Invalid read syntax: "#"

Note that the bookmark works fine until Emacs attempts to restore
the bookmarks saved to a file. In normal use, it only shows up after
Emacs is restarted.

Finding the problem:

The problem appears to be in the definition for describe-function i
help-fns.el. help-setup-xref is called with a lambda instead of a
function symbol (as it was before this code was changed).
When the bookmark is saved, the syntax for the lambda is not
parsable by read to restore it.

I don't understand the code well enough to propose an appropriate change.

I am using Aquamacs, but the code noted is the same in the master git
branch now. Version information;

Aquamacs 3.4 development
Emacs version 25.2.1

Regards,

Win Treese
treese <at> acm.org

Message #11 received at 24573 <at> debbugs.gnu.org (full text, mbox):

From: Noam Postavsky <npostavs <at> users.sourceforge.net>
To: Win Treese <treese <at> acm.org>
Cc: Dmitri Paduchikh <dpaduchikh <at> gmail.com>, 24573 <at> debbugs.gnu.org
Subject: Re: bug#24573: 25.1;
 Setting bookmark in buffer *Help* makes bookmarks non-loadable
Date: Sat, 28 Oct 2017 15:48:17 -0400

Win Treese <treese <at> acm.org> writes:

> Finding the problem:
>
> The problem appears to be in the definition for describe-function i
> help-fns.el. help-setup-xref is called with a lambda instead of a
> function symbol (as it was before this code was changed).
> When the bookmark is saved, the syntax for the lambda is not
> parsable by read to restore it.

The lambda is fine, it's the buffer which uses the unreadable print
synax: #<...>.  The following which swaps buffer objects with their name
seems to fix it, although I haven't really tested this much.

--- i/lisp/help-mode.el
+++ w/lisp/help-mode.el
@@ -756,7 +756,9 @@ help-bookmark-make-record
     (error "Cannot create bookmark - help command not known"))
   `(,@(bookmark-make-record-default 'NO-FILE 'NO-CONTEXT)
       (help-fn     . ,(car help-xref-stack-item))
-      (help-args   . ,(cdr help-xref-stack-item))
+      (help-args   . ,(mapcar (lambda (a)
+                                (if (bufferp a) (buffer-name a) a))
+                              (cdr help-xref-stack-item)))
       (position    . ,(point))
       (handler     . help-bookmark-jump)))
 

Message #14 received at 24573 <at> debbugs.gnu.org (full text, mbox):

From: Stefan Kangas <stefan <at> marxist.se>
To: Noam Postavsky <npostavs <at> users.sourceforge.net>
Cc: Dmitri Paduchikh <dpaduchikh <at> gmail.com>, 24573 <at> debbugs.gnu.org,
 Win Treese <treese <at> acm.org>
Subject: Re: bug#24573: 25.1; Setting bookmark in buffer *Help* makes
 bookmarks non-loadable
Date: Tue, 2 Jul 2019 18:22:46 +0200

[Message part 1 (text/plain, inline)]

tags 24573 patch
quit

Noam Postavsky <npostavs <at> users.sourceforge.net> writes:

> The lambda is fine, it's the buffer which uses the unreadable print
> synax: #<...>.  The following which swaps buffer objects with their name
> seems to fix it, although I haven't really tested this much.
>
> --- i/lisp/help-mode.el
> +++ w/lisp/help-mode.el
> @@ -756,7 +756,9 @@ help-bookmark-make-record
>      (error "Cannot create bookmark - help command not known"))
>    `(,@(bookmark-make-record-default 'NO-FILE 'NO-CONTEXT)
>        (help-fn     . ,(car help-xref-stack-item))
> -      (help-args   . ,(cdr help-xref-stack-item))
> +      (help-args   . ,(mapcar (lambda (a)
> +                                (if (bufferp a) (buffer-name a) a))
> +                              (cdr help-xref-stack-item)))
>        (position    . ,(point))
>        (handler     . help-bookmark-jump)))

I can confirm this bug, which I've recently stumbled into myself.

I can also confirm that Noam Postavsky's fix works.

In the interest of getting it merged as soon as possible, I'm sending
it here as a diff to be easier to apply.  I could send it as a patch
too if that will get it merged faster.  But the credit for fixing this
should fully go to Noam Postavsky.

Thanks,
Stefan Kangas

[bug24573.diff (text/x-patch, attachment)]

Message #19 received at 24573 <at> debbugs.gnu.org (full text, mbox):

From: Noam Postavsky <npostavs <at> gmail.com>
To: Stefan Kangas <stefan <at> marxist.se>
Cc: Dmitri Paduchikh <dpaduchikh <at> gmail.com>, 24573 <at> debbugs.gnu.org,
 Win Treese <treese <at> acm.org>
Subject: Re: bug#24573: 25.1;
 Setting bookmark in buffer *Help* makes bookmarks non-loadable
Date: Sat, 06 Jul 2019 14:42:35 -0400

tags 24573 fixed
close 24573 27.1
quit

Stefan Kangas <stefan <at> marxist.se> writes:
>> -      (help-args   . ,(cdr help-xref-stack-item))
>> +      (help-args   . ,(mapcar (lambda (a)
>> +                                (if (bufferp a) (buffer-name a) a))
>> +                              (cdr help-xref-stack-item)))

> I can confirm this bug, which I've recently stumbled into myself.
>
> I can also confirm that Noam Postavsky's fix works.

Ah right, kind of forgot about this.  Now pushed to master.

8d43315cfa 2019-07-06T14:34:47-04:00 "Use buffer's name for help-mode bookmarks (Bug#24573)"
https://git.savannah.gnu.org/cgit/emacs.git/commit/?id=8d43315cfa3db295736826272472ec1e394ecb60

Previous Next

GNU bug tracking system
Copyright (C) 1999 Darren O. Benham, 1997,2003 nCipher Corporation Ltd, 1994-97 Ian Jackson.