bug#25875: 26.0.50; Hang logging out of MS-Windows

[Richard Copley]

On 26 February 2017 at 15:47, Eli Zaretskii <eliz@gnu.org> wrote:
>> From: Richard Copley <rcopley@gmail.com>
>> Date: Sat, 25 Feb 2017 21:13:57 +0000
>> Cc: 25875@debbugs.gnu.org
>>
>> On 25 February 2017 at 20:36, Eli Zaretskii <eliz@gnu.org> wrote:
>> >> From: Richard Copley <rcopley@gmail.com>
>> >> Date: Sat, 25 Feb 2017 19:41:25 +0000
>> >>
>> >> Perhaps not a deadlock: I just ran "taskkill /im emacs.exe" and the
>> >> process woke up
>> >> and signaled a Lisp error:
>> >>
>> >> Debugger entered--Lisp error: (error "Attempt to delete a surrogate
>> >> minibuffer frame")
>> >>   delete-frame(#<frame *Customize Option: Package Unsigned Archives*
>> >> 0000000400a51890> t)
>> >
>> > Is this indeed a surrogate minibuffer frame?  If so, how come it's
>> > being deleted?
>>
>> An Ediff control-panel was present. The main frame was the
>> surrogate minibuffer frame for the minibufferless Ediff frame. In
>> that situation, clicking the close button on the main frame gives
>> that same error.
>
> I think this frame was an indirect reason for the hang.
>
>> I surmise that WM_QUERY_END_SESSION goes down the same code
>> path (?).
>
> Hmm... I don't see WM_QUERY_END_SESSION in our sources.  What am I
> missing?

"surmise", v.
5 a. To form a notion that the thing in question may be so, on slight
grounds or without proof; to infer conjecturally. [OED]

In other words, just a wild guess

I hadn't properly understood your subtle reference to WM_ENDSESSION
(22) in your comment on the backtrace. By the time I did notice, I
thought I'd already bombarded you enough for one evening so I didn't
correct myself.