GNU bug report logs - #25656
25.1; remember-notes-mode makes every temporary buffer created from it unkillable

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

From: Vasilij Schneidermann <v.schneidermann <at> gmail.com>
To: bug-gnu-emacs <at> gnu.org
Subject: 25.1; remember-notes-mode makes every temporary buffer created from
 it unkillable
Date: Thu, 9 Feb 2017 00:12:32 +0100

I wrote an Emacs package that takes an Org file, processes it with Org's
element API and exports to a file.  Later I've noticed that if I use it
on an Org buffer created with remember-notes-mode, it creates ~500
temporary buffers that cannot be killed.  Bisection reveals that this is
the fault of `remember-notes--kill-buffer-query` which is added locally
to `kill-buffer-query-functions` and returns nil if
`remember-notes-bury-on-kill` hasn't been customized.

This raises an interesting question, should a temporary buffer as
created by `with-temp-buffer` let-bind potentially troublesome hooks
including, but not limited to `kill-buffer-query-functions`?  Another
example coming to mind is `buffer-list-update-hook`, adding a function
to it that scans the buffer list makes creating and killing temporary
buffers an expensive action.

Message #8 received at 25656 <at> debbugs.gnu.org (full text, mbox):

From: Vasilij Schneidermann <v.schneidermann <at> gmail.com>
Cc: 25656 <at> debbugs.gnu.org
Subject: Re: [PATCH] 25.1; remember-notes-mode makes every temporary buffer
 created from it unkillable
Date: Fri, 24 Feb 2017 08:40:34 +0100

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

I wrote a simple patch for merely checking whether the buffer about to
be killed happens to be the remember-notes buffer.

[0001-Make-only-remember-notes-buffer-unkillable.patch (text/x-diff, attachment)]

Message #11 received at 25656 <at> debbugs.gnu.org (full text, mbox):

From: npostavs <at> users.sourceforge.net
To: Vasilij Schneidermann <v.schneidermann <at> gmail.com>
Cc: 25656 <at> debbugs.gnu.org
Subject: Re: bug#25656: [PATCH] 25.1;
 remember-notes-mode makes every temporary buffer created from it
 unkillable
Date: Fri, 24 Feb 2017 20:16:02 -0500

Vasilij Schneidermann <v.schneidermann <at> gmail.com> writes:

> I wrote a simple patch for merely checking whether the buffer about to
> be killed happens to be the remember-notes buffer.

I think that's a sensible change, but doesn't the fact that
remember-mode adds the hook buffer-locally mean that temp buffers (or
any other buffers) aren't affected?

    (add-hook 'kill-buffer-query-functions 'XXXX nil t)
    (with-temp-buffer
      kill-buffer-query-functions) ;=> (process-kill-buffer-query-function)

Message #14 received at 25656 <at> debbugs.gnu.org (full text, mbox):

From: Vasilij Schneidermann <v.schneidermann <at> gmail.com>
To: npostavs <at> users.sourceforge.net
Cc: 25656 <at> debbugs.gnu.org
Subject: Re: bug#25656: [PATCH] 25.1; remember-notes-mode makes every
 temporary buffer created from it unkillable
Date: Sat, 25 Feb 2017 10:47:11 +0100

> I think that's a sensible change, but doesn't the fact that
> remember-mode adds the hook buffer-locally mean that temp buffers (or
> any other buffers) aren't affected?

Hm, you're right, I can't repro this with a minimal example.  However
I'm sure that it has to do something with Org copying buffers and
failing to kill them, so I'll investigate a bit harder to see what it
could be, outside of its gratuitious use of `with-temp-buffer`.

Message #17 received at 25656 <at> debbugs.gnu.org (full text, mbox):

From: Vasilij Schneidermann <v.schneidermann <at> gmail.com>
To: npostavs <at> users.sourceforge.net
Cc: 25656 <at> debbugs.gnu.org
Subject: Re: bug#25656: [PATCH] 25.1; remember-notes-mode makes every
 temporary buffer created from it unkillable
Date: Sat, 25 Feb 2017 13:12:49 +0100

OK, I think I've figured out what's going on.  I'm calling a command in
a remember-notes buffer that happens to hold an org file.  It's set up
to be unkillable by having a locally added `kill-buffer-query-functions`
hook that returns nil.  Now, my command calls a number of things
including `org-table-export` which does a zillion of things, eventually
cloning the buffer it's working on with the
`org-export-with-buffer-copy` macro.  This macro is so good at cloning
buffers it preserves its buffer-local variables, including
`kill-buffer-query-functions`.  Although it tries killing the buffer
afterwards, it fails doing so because the hook forbids it.

The result of this avalanche of failures is that for every table cell,
an unkillable buffer is created.  The lesson from this is to be careful
with using Org's APIs, while some of them look reusable, most aren't.
While I could patch `remember-notes--kill-buffer-query` to work around
this problem, I'll just customize `remember-notes-bury-on-kill` and
raise an issue with Org's bug tracker.  Thanks for responding to this,
Noam!

Message #22 received at 25656-done <at> debbugs.gnu.org (full text, mbox):

From: Vasilij Schneidermann <v.schneidermann <at> gmail.com>
To: 25656-done <at> debbugs.gnu.org
Subject: Re: bug#25656: [PATCH] 25.1; remember-notes-mode makes every
 temporary buffer created from it unkillable
Date: Sat, 25 Feb 2017 13:15:45 +0100

Bug reason found in Org, resubmitting issue on their bug tracker.

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